Invoke-Obfuscation COMPRESS OBFUSCATION - PowerShell Module — Sigma Rule

Rule metadata and linked tags

Author: Timur Zinniatullin, oscd.community. Source status: test; severity: medium. Source dates: 2020-10-18 / 2022-11-29.

{
  "product": "windows",
  "category": "ps_module",
  "definition": "0ad03ef1-f21b-4a79-8ce8-e6900c54b65b"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 529407228c66c005f3d9ae730f9ecbfa2970b911f3b14499fa9e0975d0a94116

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Invoke-Obfuscation COMPRESS OBFUSCATION - PowerShell Module
id: 7034cbbb-cc55-4dc2-8dad-36c0b942e8f1
related:
    - id: 20e5497e-331c-4cd5-8d36-935f6e2a9a07
      type: derived
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_module
    definition: 0ad03ef1-f21b-4a79-8ce8-e6900c54b65b
detection:
    selection_4103:
        Payload|contains|all:
            - 'new-object'
            - 'text.encoding]::ascii'
        Payload|contains:
            - 'system.io.compression.deflatestream'
            - 'system.io.streamreader'
        Payload|endswith: 'readtoend'
    condition: selection_4103
falsepositives:
    - Unknown
level: medium

Original YAML and metadata in JSON

False positives

• Unknown

Source references

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