Winlogon AllowMultipleTSSessions Enable — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: medium. Source dates: 2022-09-09 / 2023-08-17.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 7aea56cc258b24c4d554b6a82fd3caaecd4e3d7a300b6f367df6058e92f7cf88

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: Winlogon AllowMultipleTSSessions Enable
id: f7997770-92c3-4ec9-b112-774c4ef96f96
status: test
description: |
  Detects when the 'AllowMultipleTSSessions' value is enabled.
  Which allows for multiple Remote Desktop connection sessions to be opened at once.
  This is often used by attacker as a way to connect to an RDP session without disconnecting the other users
references:
    - http://blog.talosintelligence.com/2022/09/lazarus-three-rats.html
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-09-09
modified: 2023-08-17
tags:
    - attack.persistence
    - attack.defense-impairment
    - attack.t1112
logsource:
    category: registry_set
    product: windows
detection:
    selection:
        TargetObject|endswith: '\Microsoft\Windows NT\CurrentVersion\Winlogon\AllowMultipleTSSessions'
        Details|endswith: DWORD (0x00000001)
    condition: selection
falsepositives:
    - Legitimate use of the multi session functionality
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate use of the multi session functionality

Source references

• http://blog.talosintelligence.com/2022/09/lazarus-three-rats.html