huntrule

PowerShell: Obfuscated IEX Invocation via Invoke-Obfuscation String/Variable Patterns

Alerts on obfuscated PowerShell IEX invocation strings built from Invoke-Obfuscation style concatenation patterns in ScriptBlockText.

FreeReviewedSigma · High · v2
Product
windows
Category
ps_script
Author
Daniel Bohannon (@Mandiant/@FireEye), oscd.community (SigmaHQ), DRL 1.1
Published
2019-11-08
Updated
2026-07-31
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 flags PowerShell script block content that matches characteristic patterns used to obfuscate variables and strings in an IEX (Invoke-Expression) invocation. Attackers rely on obfuscation to evade inspection while still executing dynamically constructed code. The detection depends on Script Block Logging telemetry that captures ScriptBlockText for matching regular expressions.

Reporting behind it

Related detections9 linkedT1027 — drag to rearrange
Malicious FIN7 Powertrash Loader Execution via Obfuscated PowerShell (via process_creation)
Suspicious XOR Obfuscated PowerShell from ClickFix Distribution
Suspicious PowerShell Executing Code from Environment Variable (via process_creation)
Suspicious In-Memory Runspace Execution via PowerShell Script Block
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
PowerShell: Obfuscated IEX Invocation via Invoke-Obfuscation String/Variable Patterns
Pivot detection · T1027 · 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.