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
Malicious Metasploit Stager Delivery via mshta Remote HTA (via process_creation)
Suspicious PowerShell Download of Disguised Payload to ProgramData
Suspicious PowerShell WebClient Download of Executable Payload
Malicious Script Host Spawning PowerShell in Gootloader Chain
Suspicious PsExec Service Launching Encoded PowerShell Payload
Suspicious PowerShell Remote Script Execution via IEX DownloadString
Malicious SharePoint ToolShell Post-Exploitation via Encoded PowerShell (via process_creation)
Suspicious In-Memory PowerShell Execution from Web Server via Automation Assembly (via image_load)
Malicious Qilin Chrome Credential Harvesting Script Execution via IPScanner (via process_creation)
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.