blue-team-tools/rules/windows/powershell/powershell_invoke_obfuscation_obfuscated_iex.yml

title: Invoke-Obfuscation Obfuscated IEX Invocation
id: 1b9dc62e-6e9e-42a3-8990-94d7a10007f7
description: "Detects all variations of obfuscated powershell IEX invocation code generated by Invoke-Obfuscation framework from the following code block \u2014 https://github.com/danielbohannon/Invoke-Obfuscation/blob/master/Out-ObfuscatedStringCommand.ps1#L873-L888"
status: experimental
author: Daniel Bohannon (@Mandiant/@FireEye), oscd.community
date: 2019/11/08
modified: 2020/08/24
tags:
    - attack.defense_evasion
    - attack.t1027
    - attack.execution
    - attack.t1059.001
    - attack.t1086  #an old one
logsource:
    product: windows
    service: powershell
    definition: Script block logging must be enabled for 4104, Module Logging must be enabled for 4103
detection:
    selection_1:
        EventID: 4104
    selection_2:
        - ScriptBlockText|re: '\$PSHome\[\s*\d{1,3}\s*\]\s*\+\s*\$PSHome\['
        - ScriptBlockText|re: '\$ShellId\[\s*\d{1,3}\s*\]\s*\+\s*\$ShellId\['
        - ScriptBlockText|re: '\$env:Public\[\s*\d{1,3}\s*\]\s*\+\s*\$env:Public\['
        - ScriptBlockText|re: '\$env:ComSpec\[(\s*\d{1,3}\s*,){2}'
        - ScriptBlockText|re: '\\\\*mdr\\\\*\W\s*\)\.Name'
        - ScriptBlockText|re: '\$VerbosePreference\.ToString\('
        - ScriptBlockText|re: '\String\]\s*\$VerbosePreference'
    selection_3:
        EventID: 4103
    selection_4:
        - Payload|re: '\$PSHome\[\s*\d{1,3}\s*\]\s*\+\s*\$PSHome\['
        - Payload|re: '\$ShellId\[\s*\d{1,3}\s*\]\s*\+\s*\$ShellId\['
        - Payload|re: '\$env:Public\[\s*\d{1,3}\s*\]\s*\+\s*\$env:Public\['
        - Payload|re: '\$env:ComSpec\[(\s*\d{1,3}\s*,){2}'
        - Payload|re: '\\\\*mdr\\\\*\W\s*\)\.Name'
        - Payload|re: '\$VerbosePreference\.ToString\('
        - Payload|re: '\String\]\s*\$VerbosePreference'
    condition: ( selection_1 and selection_2 ) or ( selection_3 and selection_4 )
falsepositives:
    - Unknown
level: high