huntrule

Windows Process Creation: Suspicious PowerShell Argument Obfuscation via Truncated Substrings

Alerts on PowerShell executions where the command line contains suspicious truncated parameter substrings (e.g., windowstyle, NoProfile, encoded/exec policy, bypass).

FreeReviewedSigma · High · v1
Product
windows
Category
process_creation
Author
Florian Roth (Nextron Systems), Daniel Bohannon (idea), Roberto Rodriguez (Fix) (SigmaHQ), DRL 1.1
Published
2019-01-16
Updated
2026-07-30
AnalysisDetection

ATT&CK techniques

Execution

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. Impact

What it detects

This rule flags Windows process executions of PowerShell (powershell.exe or pwsh.exe) where the command line contains truncated or partial substrings related to common flags and options. Attackers often obfuscate PowerShell parameters to evade straightforward detections, making these substring patterns useful for catching malformed or deliberately altered argument sequences. It relies on process creation telemetry that provides the process image path/name and the full command line string.

Reporting behind it

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Suspicious SharePoint Worker Process Spawning Command Interpreter via ToolShell
Malicious Emmenhtal JavaScript Loader Spawning Encoded PowerShell
Suspicious Python Interpreter Launching Encoded PowerShell via subprocess
Windows Process Creation: Suspicious PowerShell Argument Obfuscation via Truncated Substrings
Pivot detection · T1059.001 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.