T1036.011 Overwrite Process Arguments

> Sub-technique of: T1036

High-Level Description

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.

Kill Chain Phase

• Defense Evasion (TA0005)

Platforms: Linux

What to Check

• ] Identify if Overwrite Process Arguments technique is applicable to target environment
• ] Check Linux systems for indicators of Overwrite Process Arguments
• ] Assess detection coverage (1 detection strategies)

How to Test

Manual Testing

1. Identify Attack Surface: Determine if the target environment is susceptible to Overwrite Process Arguments by examining the target platforms (Linux).

1. Assess Existing Defenses: Review whether mitigations for T1036.011 are in place. If defenses are absent or misconfigured, this technique may be exploitable.

1. Execute Test: Use tools and methods described in the MITRE ATT&CK page and external references below.

> Note: No Atomic Red Team tests available for this technique. See Atomic Red Team GitHub for updates.

Remediation Guide

No specific mitigations documented for this technique.

Detection

Detection Strategy for Overwritten Process Arguments Masquerading

Risk Assessment

| Finding | Severity | Impact | | ------------------------------------------------ | -------- | --------------- | | Overwrite Process Arguments technique applicable | High | Defense Evasion |

CWE Categories

| CWE ID | Title | | ------- | ---------------------------- | | CWE-693 | Protection Mechanism Failure |

References

• Microsoft XorDdos Linux Stealth 2022
• Sandfly BPFDoor 2022
• Atomic Red Team - T1036.011
• MITRE ATT&CK - T1036.011