Windows Command Line Path Traversal Evasion

This brief details a technique involving the use of bogus path traversal sequences (such as '..') within command line arguments. Adversaries leverage this method to confuse security tools that perform path-based validation or filtering, allowing the execution of binaries or scripts while masquerading as legitimate system activity. This technique was documented as a potential evasion mechanism for detection controls.

Impact

The use of path traversal strings can result in bypassed security controls, such as allowlisting or path-based monitoring rules, by presenting a path that appears syntactically correct but functionally points to a different location or masks the true executable path during string analysis by security software.

Recommendation

Detection teams should analyze process creation telemetry for command line arguments containing excessive or redundant path traversal sequences.

• Deploy the provided Sigma rule to flag suspicious command lines.
• Baseline common administrative and legitimate software behavior (like Google Drive or Citrix) that may produce similar patterns to reduce noise.
• Prioritize monitoring of processes executing from 'C:\Windows' or 'C:\Windows\System32' where command line arguments contain unexpected path traversal characters.