huntrule

Windows Process Creation: PowerShell Command Lines with Hidden Base64-Encoded Keywords

Alerts on PowerShell launching with 'hidden' and embedded base64-like strings in the command line.

FreeReviewedSigma · High · v1
Product
windows
Category
process_creation
Author
John Lambert (rule) (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 creation events where PowerShell (powershell.exe/pwsh.exe) is launched with a command line containing the substring ' hidden ' and includes one or more long base64-like strings. Such obfuscation is commonly used to conceal PowerShell keywords and payload content from straightforward command-line inspection. The detection relies on process creation telemetry, including the executable path/name and the full command line.

Reporting behind it

Related detections9 linkedT1059.001 — drag to rearrange
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Suspicious PowerShell WebClient DownloadFile of Archive Payload (UAT-7237)
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: PowerShell Command Lines with Hidden Base64-Encoded Keywords
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.