Potential Mpclient.DLL Sideloading Via Defender Binaries

Hunt Hypothesis

Detects potential sideloading of “mpclient.dll” by Windows Defender processes (“MpCmdRun” and “NisSrv”) from their non-default directory.

Detection Rule

Sigma (Original)

title: Potential Mpclient.DLL Sideloading Via Defender Binaries
id: 7002aa10-b8d4-47ae-b5ba-51ab07e228b9
related:
    - id: 418dc89a-9808-4b87-b1d7-e5ae0cb6effc
      type: similar
status: test
description: Detects potential sideloading of "mpclient.dll" by Windows Defender processes ("MpCmdRun" and "NisSrv") from their non-default directory.
references:
    - https://www.sentinelone.com/blog/living-off-windows-defender-lockbit-ransomware-sideloads-cobalt-strike-through-microsoft-security-tool
author: Bhabesh Raj
date: 2022-08-01
modified: 2023-08-04
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.execution
    - attack.stealth
    - attack.t1574.001
logsource:
    product: windows
    category: process_creation
detection:
    selection:
        Image|endswith:
            - '\MpCmdRun.exe'
            - '\NisSrv.exe'
    filter_main_known_locations:
        Image|startswith:
            - 'C:\Program Files (x86)\Windows Defender\'
            - 'C:\Program Files\Microsoft Security Client\'
            - 'C:\Program Files\Windows Defender\'
            - 'C:\ProgramData\Microsoft\Windows Defender\Platform\'
            - 'C:\Windows\WinSxS\'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unlikely
level: high

KQL (Azure Sentinel)

imProcessCreate
| where (TargetProcessName endswith "\\MpCmdRun.exe" or TargetProcessName endswith "\\NisSrv.exe") and (not((TargetProcessName startswith "C:\\Program Files (x86)\\Windows Defender\\" or TargetProcessName startswith "C:\\Program Files\\Microsoft Security Client\\" or TargetProcessName startswith "C:\\Program Files\\Windows Defender\\" or TargetProcessName startswith "C:\\ProgramData\\Microsoft\\Windows Defender\\Platform\\" or TargetProcessName startswith "C:\\Windows\\WinSxS\\")))

Required Data Sources

False Positive Guidance

• Unlikely

MITRE ATT&CK Context

• Tactic: Privilege Escalation
• Tactic: Persistence
• Tactic: Execution
• Technique: T1574.001 — T1574.001

References

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