Invoke-Obfuscation COMPRESS OBFUSCATION - PowerShell

Detects Obfuscated Powershell via COMPRESS OBFUSCATION

title: Invoke-Obfuscation COMPRESS OBFUSCATION - PowerShell
id: 20e5497e-331c-4cd5-8d36-935f6e2a9a07
status: test
description: Detects Obfuscated Powershell via COMPRESS OBFUSCATION
references:
    - https://github.com/SigmaHQ/sigma/issues/1009 # (Task 19)
author: Timur Zinniatullin, oscd.community
date: 2020-10-18
modified: 2022-11-29
tags:
    - attack.stealth
    - attack.t1027
    - attack.execution
    - attack.t1059.001
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection_4104:
        ScriptBlockText|contains|all:
            - 'new-object'
            - 'text.encoding]::ascii'
        ScriptBlockText|contains:
            - 'system.io.compression.deflatestream'
            - 'system.io.streamreader'
        ScriptBlockText|endswith: 'readtoend'
    condition: selection_4104
falsepositives:
    - Unknown
level: medium

• T1027Obfuscated Files or Information
• T1059.001PowerShell

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