Invoke-Obfuscation Via Stdin

Hunt Hypothesis

Detects Obfuscated Powershell via Stdin in Scripts

Detection Rule

Sigma (Original)

title: Invoke-Obfuscation Via Stdin
id: 9c14c9fa-1a63-4a64-8e57-d19280559490
status: test
description: Detects Obfuscated Powershell via Stdin in Scripts
references:
    - https://github.com/SigmaHQ/sigma/issues/1009 # (Task28)
author: Nikita Nazarov, oscd.community
date: 2020-10-12
modified: 2026-03-16
tags:
    - attack.stealth
    - attack.t1027
    - attack.execution
    - attack.t1059.001
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|re: '(?i)(?:set).*&&\s?set.*(?:environment|invoke|\$\{?input).*&&.*"'
    condition: selection
falsepositives:
    - Unknown
level: high

KQL (Azure Sentinel)

imProcessCreate
| where TargetProcessCommandLine matches regex "(?i)(?:set).*&&\\s?set.*(?:environment|invoke|\\$\\{?input).*&&.*\""

Required Data Sources

False Positive Guidance

• Unknown

MITRE ATT&CK Context

• Tactic: Execution
• Technique: T1027 — T1027
• Technique: T1059.001 — PowerShell

References

• https://github.com/SigmaHQ/sigma/issues/1009
• SigmaHQ Rule