Windows Process Creation: Detect Obfuscated PowerShell IEX Invocation from Invoke-Obfuscation

Detects PowerShell commands showing obfuscation markers consistent with Invoke-Obfuscation-powered IEX invocation.

FreeReviewedSigma · High · v2

Product: windows
Category: process_creation
Author: Daniel Bohannon (@Mandiant/@FireEye), oscd.community (SigmaHQ), DRL 1.1
Published: 2019-11-08
Updated: 2026-07-31

ATT&CK techniques

Execution → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
- T1059.001PowerShell
Persistence
Priv Esc
Defense Evasion
- T1027Obfuscated Files or Information
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags Windows process creation events where the PowerShell command line contains multiple string/variable patterns consistent with obfuscated IEX-style invocation generated by the Invoke-Obfuscation framework. Obfuscated invocation helps attackers reduce readability, evade basic detections, and execute code with less attention to intent. Detection relies on CommandLine telemetry captured at process start, matching several regular expressions tied to specific obfuscation artifacts.

Reporting behind it

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Malicious Non-Interactive Encoded PowerShell Stager (via process_creation)

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Obfuscated Encoded PowerShell Payload Deployed - PowerShell (via powershell)

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Windows Process Creation: Detect Obfuscated PowerShell IEX Invocation from Invoke-Obfuscation

Pivot detection · T1027 · 9 related

Changelog

v2
Candidate ingested via manual entry.2026-07-31
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.

windows-powershell-obfuscated-iex-invocation-pattern-from-invoke-obfuscation-4bf943c6

title: "Windows Process Creation: Detect Obfuscated PowerShell IEX Invocation from Invoke-Obfuscation"
id: 57577c3e-766b-41c6-a20b-29e1250173ea
status: test
description: This rule flags Windows process creation events where the PowerShell command line contains multiple string/variable patterns consistent with obfuscated IEX-style invocation generated by the Invoke-Obfuscation framework. Obfuscated invocation helps attackers reduce readability, evade basic detections, and execute code with less attention to intent. Detection relies on CommandLine telemetry captured at process start, matching several regular expressions tied to specific obfuscation artifacts.
references:
  - https://github.com/danielbohannon/Invoke-Obfuscation/blob/f20e7f843edd0a3a7716736e9eddfa423395dd26/Out-ObfuscatedStringCommand.ps1#L873-L888
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_hktl_invoke_obfuscation_obfuscated_iex_commandline.yml
author: Daniel Bohannon (@Mandiant/@FireEye), oscd.community, Huntrule Team
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
license: DRL-1.1
related:
  - id: 4bf943c6-5146-4273-98dd-e958fd1e3abf
    type: derived

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