User Added to Remote Desktop Users Group — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems). Source status: test; severity: high. Source dates: 2021-12-06 / 2022-09-09.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: b775149c19ee7df8e80b03f6e36d1a4b25dcc1fcf84143e245a983f0620a63b9

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: User Added to Remote Desktop Users Group
id: ffa28e60-bdb1-46e0-9f82-05f7a61cc06e
related:
    - id: ad720b90-25ad-43ff-9b5e-5c841facc8e5 # Admin groups
      type: similar
    - id: 10fb649c-3600-4d37-b1e6-56ea90bb7e09 # Privileged groups
      type: similar
status: test
description: Detects addition of users to the local Remote Desktop Users group via "Net" or "Add-LocalGroupMember".
references:
    - https://www.microsoft.com/security/blog/2021/11/16/evolving-trends-in-iranian-threat-actor-activity-mstic-presentation-at-cyberwarcon-2021/
author: Florian Roth (Nextron Systems)
date: 2021-12-06
modified: 2022-09-09
tags:
    - attack.initial-access
    - attack.persistence
    - attack.lateral-movement
    - attack.t1133
    - attack.t1136.001
    - attack.t1021.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_main:
        - CommandLine|contains|all:
              - 'localgroup '
              - ' /add'
        - CommandLine|contains|all:
              - 'Add-LocalGroupMember '
              - ' -Group '
    selection_group:
        CommandLine|contains:
            - 'Remote Desktop Users'
            - 'Utilisateurs du Bureau à distance' # French for "Remote Desktop Users"
            - 'Usuarios de escritorio remoto' # Spanish for "Remote Desktop Users"
    condition: all of selection_*
falsepositives:
    - Administrative activity
level: high

Original YAML and metadata in JSON

False positives

• Administrative activity

Source references

• https://www.microsoft.com/security/blog/2021/11/16/evolving-trends-in-iranian-threat-actor-activity-mstic-presentation-at-cyberwarcon-2021/