Microsoft Defender Blocked from Loading Unsigned DLL — Sigma Rule

{
  "product": "windows",
  "service": "security-mitigations"
}

title: Microsoft Defender Blocked from Loading Unsigned DLL
id: 0b0ea3cc-99c8-4730-9c53-45deee2a4c86
status: test
description: Detects Code Integrity (CI) engine blocking Microsoft Defender's processes (MpCmdRun and NisSrv) from loading unsigned DLLs which may be an attempt to sideload arbitrary DLL
references:
    - https://www.sentinelone.com/blog/living-off-windows-defender-lockbit-ransomware-sideloads-cobalt-strike-through-microsoft-security-tool
author: Bhabesh Raj
date: 2022-08-02
modified: 2022-09-28
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.execution
    - attack.stealth
    - attack.t1574.001
logsource:
    product: windows
    service: security-mitigations
detection:
    selection:
        EventID:
            - 11
            - 12 # MDE: ExploitGuardNonMicrosoftSignedBlocked
        ProcessPath|endswith:
            - '\MpCmdRun.exe'
            - '\NisSrv.exe'
    condition: selection
falsepositives:
    - Unknown
level: high