title: Invoke-Obfuscation Via Stdin
id: 86b896ba-ffa1-4fea-83e3-ee28a4c915c7
description: Detects Obfuscated Powershell via Stdin in Scripts
status: experimental
author: Nikita Nazarov, oscd.community
date: 2020/10/12
references:
     - https://github.com/Neo23x0/sigma/issues/1009 #(Task28)
tags:
    - attack.defense_evasion
    - attack.t1027
    - attack.execution
    - attack.t1059.001
logsource:
    product: windows
    service: powershell
    definition: Script block logging must be enabled for 4104, Module Logging must be enable for 4103
detection:
    selection_1:
        EventID: 4104
        ScriptBlockText|re: '(?i).*(set).*&&\s?set.*(environment|invoke|\${?input).*&&.*"'
    selection_2:
        EventID: 4103
        Payload|re: '(?i).*(set).*&&\s?set.*(environment|invoke|\${?input).*&&.*"'
    condition: 1 of them
falsepositives:
    - Unknown
level: high