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
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Suspicious PowerShell EncodedCommand Spawned From Command Shell via Process Creation
Suspicious Script Download via Curl and PowerShell by Dohdoor
Malicious Mass Hyper-V Virtual Machine Shutdown via PowerShell by Kraken Ransomware
Suspicious PowerShell WebClient DownloadFile of Archive Payload (UAT-7237)
Suspicious SharePoint Worker Process Spawning Command Interpreter via ToolShell
Malicious Emmenhtal JavaScript Loader Spawning Encoded PowerShell
Suspicious Python Interpreter Launching Encoded PowerShell via subprocess
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.