Microsoft Defender Blocked from Loading Unsigned DLL

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

Sigma rule (View on GitHub)

 1title: Microsoft Defender Blocked from Loading Unsigned DLL
 2id: 0b0ea3cc-99c8-4730-9c53-45deee2a4c86
 3status: test
 4description: 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
 5references:
 6    - https://www.sentinelone.com/blog/living-off-windows-defender-lockbit-ransomware-sideloads-cobalt-strike-through-microsoft-security-tool
 7author: Bhabesh Raj
 8date: 2022-08-02
 9modified: 2022-09-28
10tags:
11    - attack.defense-evasion
12    - attack.t1574.002
13logsource:
14    product: windows
15    service: security-mitigations
16detection:
17    selection:
18        EventID:
19            - 11
20            - 12 # MDE: ExploitGuardNonMicrosoftSignedBlocked
21        ProcessPath|endswith:
22            - '\MpCmdRun.exe'
23            - '\NisSrv.exe'
24    condition: selection
25falsepositives:
26    - Unknown
27level: high

References

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