Invoke-Obfuscation Obfuscated IEX Invocation — Sigma Rule

Rule metadata and linked tags

Author: Daniel Bohannon (@Mandiant/@FireEye), oscd.community. Source status: test; severity: high. Source dates: 2019-11-08 / 2026-03-16.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 420f6e1e15375b88b54297e270b67e8a80173c07afdd5dc009fc21e272c164db

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Invoke-Obfuscation Obfuscated IEX Invocation
id: 4bf943c6-5146-4273-98dd-e958fd1e3abf
status: test
description: Detects all variations of obfuscated powershell IEX invocation code generated by Invoke-Obfuscation framework from the following code block
references:
    - https://github.com/danielbohannon/Invoke-Obfuscation/blob/f20e7f843edd0a3a7716736e9eddfa423395dd26/Out-ObfuscatedStringCommand.ps1#L873-L888
author: 'Daniel Bohannon (@Mandiant/@FireEye), oscd.community'
date: 2019-11-08
modified: 2026-03-16
tags:
    - attack.stealth
    - attack.t1027
    - attack.execution
    - attack.t1059.001
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        - CommandLine|re: '\$PSHome\[\s*\d{1,3}\s*\]\s*\+\s*\$PSHome\['
        - CommandLine|re: '\$ShellId\[\s*\d{1,3}\s*\]\s*\+\s*\$ShellId\['
        - CommandLine|re: '\$env:Public\[\s*\d{1,3}\s*\]\s*\+\s*\$env:Public\['
        - CommandLine|re: '\$env:ComSpec\[(?:\s*\d{1,3}\s*,){2}'
        - CommandLine|re: '\*mdr\*\W\s*\)\.Name'
        - CommandLine|re: '\$VerbosePreference\.ToString\('
        - CommandLine|re: '\[String\]\s*\$VerbosePreference'
    condition: selection
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://github.com/danielbohannon/Invoke-Obfuscation/blob/f20e7f843edd0a3a7716736e9eddfa423395dd26/Out-ObfuscatedStringCommand.ps1#L873-L888