ScreenConnect User Database Modification - Security

Description

This detects file modifications to the temporary xml user database file indicating local user modification in the ScreenConnect server. This will occur during exploitation of the ScreenConnect Authentication Bypass vulnerability (CVE-2024-1709) in versions <23.9.8, but may also be observed when making legitimate modifications to local users or permissions. This requires an Advanced Auditing policy to log a successful Windows Event ID 4663 events and with a SACL set on the directory.

Query · sigma

selection:
  EventID: 4663
  ObjectType: File
  AccessMask: '0x6'
  ObjectName|endswith: .xml
  ObjectName|contains|all:
  - Temp
  - ScreenConnect
  ProcessName|contains: ScreenConnect.Service.exe
condition: selection

Known false positives

  • This will occur legitimately as well and will result in some benign activity.
Raw source ScreenConnect User Database Modification - Security · Sigma
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Published by SigmaHQ/sigma ↗, licensed under Detection Rule License 1.1 ↗. Reproduced here unmodified. 
title: ScreenConnect User Database Modification - Security
id: 4109cb6a-a4af-438a-9f0c-056abba41c6f
related:
    - id: 1a821580-588b-4323-9422-660f7e131020
      type: similar
status: test
description: |
    This detects file modifications to the temporary xml user database file indicating local user modification in the ScreenConnect server.
    This will occur during exploitation of the ScreenConnect Authentication Bypass vulnerability (CVE-2024-1709) in versions <23.9.8, but may also be observed when making legitimate modifications to local users or permissions.
    This requires an Advanced Auditing policy to log a successful Windows Event ID 4663 events and with a SACL set on the directory.
references:
    - https://www.connectwise.com/company/trust/security-bulletins/connectwise-screenconnect-23.9.8
    - https://www.cve.org/CVERecord?id=CVE-2024-1709
    - https://www.huntress.com/blog/a-catastrophe-for-control-understanding-the-screenconnect-authentication-bypass
author: Matt Anderson, Kris Luzadre, Andrew Schwartz, Huntress
date: 2024-02-20
tags:
    - cve.2024-1709
    - detection.emerging-threats
    - attack.defense-impairment
logsource:
    product: windows
    service: security
    definition: 'Requirements: SACLs must be enabled for the ScreenConnect directory'
detection:
    selection:
        EventID: 4663
        ObjectType: 'File'
        AccessMask: '0x6'
        ObjectName|endswith: '.xml'
        ObjectName|contains|all:
            - 'Temp'
            - 'ScreenConnect'
        ProcessName|contains: 'ScreenConnect.Service.exe'
    condition: selection
falsepositives:
    - This will occur legitimately as well and will result in some benign activity.
level: medium

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