Microsoft Defender Blocked from Loading Unsigned DLL — Sigma Rule

Rule metadata and linked tags

Author: Bhabesh Raj. Source status: test; severity: high. Source dates: 2022-08-02 / 2022-09-28.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 8d8e33f59ed44ede51161793e1064d0b1c711623eab9b879275ae4f33a662f85

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: 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

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://www.sentinelone.com/blog/living-off-windows-defender-lockbit-ransomware-sideloads-cobalt-strike-through-microsoft-security-tool