ScreenConnect_modification_sigma_rule.yml

ScreenConnect_modification_sigma_rule.yml

title: ScreenConnect User Database Modification
id: 4109cb6a-a4af-438a-9f0c-056abba41c6f
status: experimental
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.huntress.com/blog/a-catastrophe-for-control-understanding-the-screenconnect-authentication-bypass
    - https://www.cve.org/CVERecord?id=CVE-2024-1709
author: Huntress DE&TH Team
date: 2024/02/20
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:
    - Unknown
level: medium
tags:
    - cve.2024.1709