Indirect Command Execution via forfiles.exe

The Windows utility 'forfiles.exe' is a legitimate system tool designed to select files in a directory and run a command on each file. However, threat actors leverage this functionality for indirect command execution to bypass security controls that monitor for direct process launches or suspicious command-line patterns. By utilizing the '/c' flag, an attacker can specify a custom command string that forfiles.exe executes on behalf of the attacker, effectively masking the true origin of the malicious process. This technique is frequently observed in post-exploitation scenarios where adversaries maintain persistence or perform lateral movement while attempting to evade detection by security software. Defenders must identify process creation events where forfiles.exe acts as the parent, particularly when the command line includes the '/c' switch, as this is a hallmark of indirect execution.

Impact

Successful abuse of forfiles.exe allows an attacker to execute arbitrary code with the permissions of the user or system account running the utility. This can lead to full system compromise, unauthorized data exfiltration, or the deployment of additional malicious payloads. While common in 'living off the land' post-exploitation activity, this technique remains a significant risk for environments where command-line telemetry is the primary defense against scripting-based attacks.

Recommendation

Prioritize the implementation of process creation monitoring to identify potential abuse of system utilities.

• Deploy the Sigma rule below to detect suspicious parent-child relationships involving forfiles.exe.
• Establish a baseline for legitimate administrative usage of forfiles.exe within the environment to reduce false positives.
• Enable Sysmon or EDR process creation logging to capture parent-child process relationships and command-line arguments.
• Investigate any forfiles.exe processes that execute unexpected binaries, especially those originating from unexpected parent processes or locations.