Command Execution via ForFiles Utility

The Windows forfiles utility is a legitimate command-line tool that allows batch processing of files. However, adversaries can abuse forfiles to execute arbitrary commands indirectly, bypassing security controls and evading detection. This technique, known as “Indirect Command Execution,” involves using forfiles to invoke other processes or run scripts, effectively hiding the malicious intent behind a trusted Windows utility. This method can be used to download payloads, execute scripts, or perform other malicious activities under the guise of legitimate forfiles activity. The attacks leveraging this technique have been observed since at least 2025. This matters for defenders because it allows attackers to blend in with normal system activity and makes it harder to identify malicious behavior.

Attack Chain

1. An attacker gains initial access to the system through an unknown vector (e.g., phishing or exploiting a vulnerability).
2. The attacker leverages forfiles.exe to execute a command by using the /c or -c argument.
3. The attacker crafts the command to execute a script, download a file, or perform another malicious action.
4. forfiles.exe launches the specified command, which could involve PowerShell, cmd.exe, or another scripting engine.
5. The script executes, downloading a malicious payload from an external source.
6. The payload is saved to disk and executed, establishing persistence.
7. The attacker uses the compromised system to move laterally within the network.
8. The final objective is achieved, such as data exfiltration or ransomware deployment.

Impact

Successful exploitation can lead to a compromised system, allowing attackers to perform various malicious activities, including data theft, malware installation, and lateral movement within the network. The impact is dependent on the attacker’s objectives and the level of access gained. By using forfiles, attackers can bypass traditional security measures and remain undetected for longer periods. The severity is medium as it requires initial access and relies on a dual-use tool.

Recommendation

• Deploy the Sigma rule Command Execution via ForFiles to your SIEM to detect suspicious command execution patterns involving forfiles.exe.
• Monitor process creation events for instances of forfiles.exe with the /c or -c arguments, excluding known legitimate uses as specified in the Sigma rule.
• Investigate any instances of forfiles.exe execution where the command line contains suspicious parameters or attempts to execute scripts from unusual locations (e.g., the user’s temporary directory).
• Enable Sysmon process creation logging (Event ID 1) to gain more detailed information about process executions, including command-line arguments and parent-child relationships.
• Review and audit the usage of forfiles.exe across the environment to identify any unauthorized or suspicious activity.