Gzip Archive Decode Via PowerShell — Sigma Rule

Rule metadata and linked tags

Author: Hieu Tran. Source status: test; severity: medium. Source dates: 2023-03-13 / not supplied.

{
  "product": "windows",
  "category": "process_creation"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: f4d17159b673eef4c41711bd398e336f838028295e00ef9b4148b438030a611f

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: Gzip Archive Decode Via PowerShell
id: 98767d61-b2e8-4d71-b661-e36783ee24c1
status: test
description: Detects attempts of decoding encoded Gzip archives via PowerShell.
references:
    - https://www.zscaler.com/blogs/security-research/onenote-growing-threat-malware-distribution
author: Hieu Tran
date: 2023-03-13
tags:
    - attack.command-and-control
    - attack.t1132.001
logsource:
    product: windows
    category: process_creation
detection:
    selection:
        CommandLine|contains|all:
            - 'GZipStream'
            - '::Decompress'
    condition: selection
falsepositives:
    - Legitimate administrative scripts may use this functionality. Use "ParentImage" in combination with the script names and allowed users and applications to filter legitimate executions
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate administrative scripts may use this functionality. Use "ParentImage" in combination with the script names and allowed users and applications to filter legitimate executions

Source references

• https://www.zscaler.com/blogs/security-research/onenote-growing-threat-malware-distribution