Portable Gpg.EXE Execution — Sigma Rule

Rule metadata and linked tags

Author: frack113, Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: medium. Source dates: 2023-08-06 / 2023-11-10.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 3f2148a176c2ec8cff3b2755468fe0022dc4aa08e562b9114573e4f6fbab8bc5

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: Portable Gpg.EXE Execution
id: 77df53a5-1d78-4f32-bc5a-0e7465bd8f41
status: test
description: Detects the execution of "gpg.exe" from uncommon location. Often used by ransomware and loaders to decrypt/encrypt data.
references:
    - https://www.trendmicro.com/vinfo/vn/threat-encyclopedia/malware/ransom.bat.zarlock.a
    - https://securelist.com/locked-out/68960/
    - https://github.com/redcanaryco/atomic-red-team/blob/c4097dc7ed14d7f7d08c89d148c4307097e8c294/atomics/T1486/T1486.md
author: frack113, Nasreddine Bencherchali (Nextron Systems)
date: 2023-08-06
modified: 2023-11-10
tags:
    - attack.impact
    - attack.t1486
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        - Image|endswith:
              - '\gpg.exe'
              - '\gpg2.exe'
        - OriginalFileName: 'gpg.exe'
        - Description: 'GnuPG’s OpenPGP tool'
    filter_main_legit_location:
        Image|contains:
            - ':\Program Files (x86)\GNU\GnuPG\bin\'
            - ':\Program Files (x86)\GnuPG VS-Desktop\'
            - ':\Program Files (x86)\GnuPG\bin\'
            - ':\Program Files (x86)\Gpg4win\bin\'
    condition: selection and not 1 of filter_main_*
level: medium

Original YAML and metadata in JSON

False positives

No reviewed association in this snapshot.

Source references

• https://www.trendmicro.com/vinfo/vn/threat-encyclopedia/malware/ransom.bat.zarlock.a
• https://securelist.com/locked-out/68960/
• https://github.com/redcanaryco/atomic-red-team/blob/c4097dc7ed14d7f7d08c89d148c4307097e8c294/atomics/T1486/T1486.md