Description
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](https://attack.mitre.org/techniques/T1055/012) 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](https://attack.mitre.org/techniques/T1106) <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](https://attack.mitre.org/techniques/T1134/004)) to manipulate or further evade process-based detections.
Threat-Mapped Scoring
ATT&CK Kill Chain Metadata
- Tactics: defense-evasion
- Platforms: Windows
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Detection Guidance:
Detection of process argument spoofing may be difficult as adversaries may momentarily modify stored arguments used for malicious execution. These changes may bypass process creation detection and/or later process memory analysis. Consider monitoring for [Process Hollowing](https://attack.mitre.org/techniques/T1055/012), which includes monitoring for process creation (especially those in a suspended state) as well as access and/or modifications of these processes (especially by the parent process) via Windows API calls.(Citation: Nviso Spoof Command Line 2020)(Citation: Mandiant Endpoint Evading 2019) Analyze process behavior to determine if a process is performing actions it usually does not and/or do no align with its logged command-line arguments.