huntrule

PowerShell Downgrade Attempts via -Version 2 on Windows Process Creation

Alerts on PowerShell executions specifying a -Version 2 argument, consistent with potential downgrade attempts.

FreeReviewedSigma · Medium · v1
Product
windows
Category
process_creation
Author
Harish Segar (rule) (SigmaHQ), DRL 1.1
Published
2020-03-20
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 PowerShell processes where the command line includes indications of using the -version parameter set to 2. Attackers may downgrade the PowerShell engine version to change available defenses and behavior, including reducing protections that depend on newer versions. It relies on Windows process creation telemetry, specifically the process image path ending in powershell.exe and matching command-line substrings that contain version 2 arguments.

Reporting behind it

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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)
PowerShell Downgrade Attempts via -Version 2 on Windows Process Creation
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.