Suspicious Invoke-Obfuscation COMPRESS OBFUSCATION (via process_creation)

title: Suspicious Invoke-Obfuscation COMPRESS OBFUSCATION (via process_creation)
id: 114d6671-4c42-5786-bb61-f112ce457d0d
status: stable
description: This rule detects Obfuscated Powershell via COMPRESS OBFUSCATION
references:
    - https://attack.mitre.org/techniques/T1059/001/
    - https://attack.mitre.org/techniques/T1027/
    - https://github.com/SigmaHQ/sigma/issues/1009
author: Huntrule Team
date: 2026-04-19
tags:
    - attack.stealth
    - attack.t1027
    - attack.execution
    - attack.t1059.001
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains|all:
            - 'new-object'
            - 'text.encoding]::ascii'
        CommandLine|contains:
            - 'system.io.compression.deflatestream'
            - 'system.io.streamreader'
            - 'readtoend('
    condition: selection
falsepositives:
    - Unknown
level: medium