Process Argument Spoofing
Where this stands
A reviewer read the telemetry and concluded there is nothing here to detect that a sibling technique does not already cover.
AN0126's own description names the mechanism precisely: a process is spawned CREATE_SUSPENDED with benign arguments, the PEB is then overwritten via WriteProcessMemory, and the thread is resumed with the malicious arguments live. Neither logsource this brief supplies can see that overwrite. Sysmon EventID 10 (process_access) fires on an OpenProcess call, and the adversary never makes one here -- CreateProcess() already hands the caller a process handle for the child it just created, exactly the 'injector creates the victim itself and already holds the handle' reasoning already recorded against T1055.012's EID10 leg in this corpus, an independent case of the identical Windows behaviour. Sysmon has no event for a WriteProcessMemory call in general, so the PEB overwrite itself is invisible regardless. […]
Covered instead by T1055.012.
What the technique is
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. 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 WriteProcessMemory() function) then resume process execution with malicious arguments. 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. This behavior may also be combined with other tricks (such as Parent PID Spoofing) to manipulate or further evade process-based detections.
Read it on attack.mitre.orgWhat MITRE says you would watch
- AN0126
Inconsistencies between process command-line arguments logged at creation time and subsequent process behavior. Defender perspective: monitoring for processes launched in a suspended state, followed by memory modifications (e.g., WriteProcessMemory targeting the PEB) that overwrite arguments before execution resumes. Detection also includes observing anomalous behaviors from processes whose logged arguments do not align with executed activity (e.g., network connections, file writes, or registry modifications).
Technique names and descriptions © MITRE ATT&CK®, CC BY 4.0. Not endorsed by MITRE.