System Language Discovery via Reg.Exe — Sigma Rule

Rule metadata and linked tags

Author: Marco Pedrinazzi (@pedrinazziM) (InTheCyber). Source status: experimental; severity: medium. Source dates: 2026-01-09 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 533b9cc3f112b7af6b3399ae079ce18b03cd0ae29159e0290b20142b2653ff5e

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: System Language Discovery via Reg.Exe
id: c43a5405-e8e1-4221-9ac9-dbe3fa14e886
status: experimental
description: |
    Detects the usage of Reg.Exe to query system language settings.
    Attackers may discover the system language to determine the geographic location of victims, customize payloads for specific regions,
    or avoid targeting certain locales to evade detection.
references:
    - https://scythe.io/threat-thursday/threatthursday-darkside-ransomware
author: Marco Pedrinazzi (@pedrinazziM) (InTheCyber)
date: 2026-01-09
tags:
    - attack.discovery
    - attack.t1614.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\reg.exe'
        - OriginalFileName: 'reg.exe'
    selection_cli:
        CommandLine|contains|all:
            - 'query'
            - 'Control\Nls\Language'
    condition: all of selection_*
falsepositives:
    - Unknown
level: medium
regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_reg_system_language_discovery/info.yml
simulation:
    - type: atomic-red-team
      name: Discover System Language by Registry Query
      technique: T1614.001
      atomic_guid: 631d4cf1-42c9-4209-8fe9-6bd4de9421be

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://scythe.io/threat-thursday/threatthursday-darkside-ransomware