Invoke-Obfuscation COMPRESS OBFUSCATION - Security — 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",
  "service": "security",
  "definition": "The 'System Security Extension' audit subcategory need to be enabled to log the EID 4697"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 3fbb0397bc63c6983ac9a97d28d3b0a77d88a1a42041e3a35caaf29ef948ce3e

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 - Security
id: 7a922f1b-2635-4d6c-91ef-af228b198ad3
related:
    - id: 175997c5-803c-4b08-8bb0-70b099f47595
      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
    service: security
    definition: The 'System Security Extension' audit subcategory need to be enabled to log the EID 4697
detection:
    selection:
        EventID: 4697
        ServiceFileName|contains|all:
            - 'new-object'
            - 'text.encoding]::ascii'
            - 'readtoend'
        ServiceFileName|contains:
            - 'system.io.compression.deflatestream'
            - 'system.io.streamreader'
    condition: selection
falsepositives:
    - Unknown
level: medium

Original YAML and metadata in JSON

False positives

• Unknown

Source references

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