Windows MpCmdRun RemoveDefinitions Execution

SPLUNK detection rule by Teoderick Contreras, Splunk · Apache-2.0

This detection identifies the execution of MpCmdRun.exe with the "-RemoveDefinitions" argument, which is used to remove definitions from the Windows Malware Protection Engine. This behavior can be significant as it might indicate potential malware activity or attempts to bypass security measures.

name: Windows MpCmdRun RemoveDefinitions Execution
id: b2442e49-bd3f-4685-a2dc-2bdc292563bf
version: 4
creation_date: '2026-03-16'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: |
    This detection identifies the execution of MpCmdRun.exe with the "-RemoveDefinitions" argument, which is used to remove definitions from the Windows Malware Protection Engine.
    This behavior can be significant as it might indicate potential malware activity or attempts to bypass security measures.
data_source:
    - Sysmon EventID 1
    - Windows Event Log Security 4688
    - CrowdStrike ProcessRollup2
search: |-
    | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime
      from datamodel=Endpoint.Processes where
      (Processes.process_name ="MpCmdRun.exe" OR Processes.original_file_name = MpCmdRun.exe)
      Processes.process = "*-RemoveDefinitions *"
      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.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_mpcmdrun_removedefinitions_execution_filter`
how_to_implement: |
    The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
known_false_positives: |
    Administrators may execute this command for testing or auditing.
references:
    - https://cert.gov.ua/article/6284730
drilldown_searches:
    - name: View the detection results for - "$user$" and "$dest$"
      search: '%original_detection_search% | search  user = "$user$" dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$user$" and "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$", "$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: An instance of [$process_name$] attempting to remove definitions from the Windows Malware Protection Engine via the Command [$process$] on [$dest$] by user [$user$].
        - field: user
          type: user
          score: 20
          message: An instance of [$process_name$] attempting to remove definitions from the Windows Malware Protection Engine via the Command [$process$] on [$dest$] by user [$user$].
threat_objects:
    - field: parent_process_name
      type: parent_process_name
    - field: process_name
      type: process_name
analytic_story:
    - BlankGrabber Stealer
asset_type: Endpoint
mitre_attack_id:
    - T1685
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1562.001/mpcmdrun_remove/mpcmdrun_remove.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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