Windows Defender MpClient.dll Loaded by Non-Defender Process

name: Windows Defender MpClient.dll Loaded by Non-Defender Process
id: 20f72601-2a92-47bc-8776-177671bbe189
version: 1
creation_date: '2026-08-19'
modification_date: '2026-08-19'
author: Onur Mustafa Erdogan, Splunk
status: production
type: Anomaly
description: |-
    The following analytic detects mpclient.dll, the Windows Defender client API library, being loaded by a process that is not part of the Windows Defender platform.
    mpclient.dll exposes the API surface used to drive on-demand Defender scans (IOAV, MpScan). In the ShieldBreak exploit, the attacker binary loads mpclient.dll directly and calls its scan APIs against an object-manager path in order to trigger a Defender scan against attacker-controlled content as part of a race condition targeting Defender's placeholder-hydration behavior.
    If confirmed malicious, this activity indicates an attempt to weaponize Windows Defender's own scanning pipeline for local privilege escalation.
data_source:
    - Sysmon EventID 7
search: |-
    | tstats `security_content_summariesonly`
      count min(_time) as firstTime
            max(_time) as lastTime
    from datamodel=Endpoint.Processes where
    
    Processes.loaded_file="mpclient.dll"
    NOT Processes.user IN ("* SERVICE", "SYSTEM")
    NOT Processes.process_path="*\MpCmdRun.exe"
    Processes.process_path IN (
        "*:\\AppData\\Local\\Temp\\*",
        "*:\\Perflogs\\*",
        "*:\\ProgramData\\*",
        "*:\\Temp\\*",
        "*:\\Users\\*",
        "*:\\Windows\\Tasks\\*"
    )
    by Processes.action Processes.dest Processes.original_file_name Processes.parent_process
       Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id
       Processes.parent_process_name Processes.parent_process_path Processes.loaded_file Processes.process
       Processes.process_exec Processes.process_guid Processes.process_hash Processes.process_id
       Processes.process_integrity_level Processes.process_name Processes.process_path
       Processes.user Processes.user_id Processes.vendor_product
    
    | `drop_dm_object_name(Processes)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `windows_defender_mpclient_dll_loaded_by_non_defender_process_filter`
how_to_implement: |-
    To successfully implement this search, you need to be ingesting logs with the driver/module loaded from your endpoints.
    If you are using Sysmon, configuration must explicitly include image loading events targeting mpclient.dll.
known_false_positives: |-
    Third-party security products or custom AV-integration tooling that legitimately calls into the Defender client API may load mpclient.dll outside the Defender platform directories. Filter as necessary for your environment.
references:
    - https://www.cyderes.com/howler-cell/rogueplanet-windows-zero-day
    - https://www.threatlocker.com/blog/nightmareeclipse-releases-new-poc-shieldbreak-exploits-same-weakness-as-rogueplanet
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: The [$loaded_file$] DLL was loaded by a suspicious process [$process_path$] on [$dest$]
threat_objects:
    - field: process_path
      type: file_path
analytic_story:
    - RoguePlanet
asset_type: Endpoint
mitre_attack_id:
    - T1068
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint