huntrule

Windows PowerShell Base64-Encoded WMI Class Invocation

Flags PowerShell command lines containing Base64 fragments indicative of WMI class usage (e.g., ShadowCopy, ScheduledJob) on Windows.

FreeReviewedSigma · High · v1
Product
windows
Category
process_creation
Author
Christian Burkard (Nextron Systems), Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2023-01-30
Updated
2026-07-30
AnalysisDetection

ATT&CK techniques

Execution → Defense Evasion

  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 identifies process executions of PowerShell (powershell.exe or pwsh.exe) where the command line contains Base64-like fragments corresponding to WMI class names such as Win32_ShadowCopy, Win32_ScheduledJob, Win32_Process, Win32_UserAccount, and Win32_LoggedOnUser. Attackers may encode WMI-related payloads to obscure intent and evade simple command-line inspections. The detection relies on process creation telemetry, specifically the executable path and command-line contents of PowerShell executions containing those encoded class indicators.

Reporting behind it

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Suspicious Encoded PowerShell Using Base64 Stream Decompression Routines (via process_creation)
Suspicious PowerShell In-Memory Execution with AES Decryption
Suspicious Encoded PowerShell Command Execution
Suspicious PEAKLIGHT Memory-Only PowerShell Downloader Flags (via process_creation)
Obfuscated PowerShell Script: Indirect Cmdlet Execution via ExportedCommands Array Index
Windows PowerShell Base64-Encoded WMI Class Invocation
Pivot detection · T1027 · 9 related

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