huntrule

Suspicious PowerShell Module Usage with Hidden/Encoded Execution Parameters on Windows

Flags hidden or encoded PowerShell invocations that decode/execute code or download-and-execute patterns, while filtering a Chocolatey installer snippet.

FreeReviewedSigma · High · v2
Product
windows
Category
ps_module
Author
Florian Roth (Nextron Systems), Jonhnathan Ribeiro (SigmaHQ), DRL 1.1
Published
2017-03-05
Updated
2026-07-31
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 PowerShell executions that include hidden or non-interactive invocation parameters combined with encoded or staged command execution patterns. It matters because attackers often use PowerShell to run payloads covertly via Base64 decoding, IEX-based execution, or encoded command options to reduce visibility. The detection relies on Windows telemetry containing PowerShell module ContextInfo strings with specific combinations of flags and command fragments (e.g., -nop, hidden windowing, -c with Convert.FromBase64String or iex/New-Object).

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)
Suspicious PowerShell Module Usage with Hidden/Encoded Execution Parameters on Windows
Pivot detection · T1059.001 · 9 related

Changelog

v2
  1. v2
    Candidate ingested via manual entry.2026-07-31
  2. v1
    No changelog recorded for this version.2026-07-30

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