huntrule

Windows PowerShell Base64 Command Line Executing IEX

Identifies Windows PowerShell processes with Base64-encoded command-line content that contains an IEX execution pattern.

FreeReviewedSigma · High · v1
Product
windows
Category
process_creation
Author
Florian Roth (Nextron Systems) (SigmaHQ), DRL 1.1
Published
2019-08-23
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 command lines that include a Base64-like payload containing an encoded "IEX" invocation. Attackers commonly use IEX to execute attacker-supplied PowerShell code, and encoding can help evade simple command-line inspection. The detection relies on process creation telemetry, matching specific Base64 substrings and encoded "IEX" patterns in the CommandLine field.

Reporting behind it

Related detections9 linkedT1059.001 — drag to rearrange
Malicious Metasploit Stager Delivery via mshta Remote HTA (via process_creation)
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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 PowerShell Base64 Command Line Executing IEX
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.