Possible Encoded PowerShell Patterns In CommandLine (via process_creation)

title: Possible Encoded PowerShell Patterns In CommandLine (via process_creation)
id: a5a96538-5f2b-5577-bcc9-e2cea0fa4201
status: stable
description: This rule detects specific combinations of encoding methods in PowerShell via the commandline
references:
    - https://attack.mitre.org/techniques/T1059/001/
    - https://attack.mitre.org/techniques/T1027/
    - https://speakerdeck.com/heirhabarov/hunting-for-powershell-abuse?slide=65
author: Huntrule Team
date: 2026-04-21
tags:
    - attack.stealth
    - attack.t1027
    - attack.execution
    - attack.t1059.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith:
              - '\powershell.exe'
              - '\pwsh.exe'
        - OriginalFileName:
              - 'PowerShell.EXE'
              - 'pwsh.dll'
    selection_to_1:
        CommandLine|contains:
            - 'ToInt'
            - 'ToDecimal'
            - 'ToByte'
            - 'ToUint'
            - 'ToSingle'
            - 'ToSByte'
    selection_to_2:
        CommandLine|contains:
            - 'ToChar'
            - 'ToString'
            - 'String'
    selection_gen_1:
        CommandLine|contains|all:
            - 'char'
            - 'join'
    selection_gen_2:
        CommandLine|contains|all:
            - 'split'
            - 'join'
    condition: selection_img and (all of selection_to_* or 1 of selection_gen_*)
falsepositives:
    - Unknown
level: low