Invoke-Obfuscation COMPRESS OBFUSCATION - PowerShell — 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_script",
  "definition": "Requirements: Script Block Logging must be enabled"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 199d2dc23f8f69d6f9323fd76c8b7fcb98e83ea4e66d2cc9d2320c4e1d51435f

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
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

Original YAML and metadata in JSON

False positives

• Unknown

Source references

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