Windows Compatibility Telemetry Suspicious Child Process

name: Windows Compatibility Telemetry Suspicious Child Process
id: 56fe46ca-ffef-46fe-8f0e-5cd4b7b4cc0c
version: 7
date: '2026-03-10'
author: Steven Dick
status: production
type: TTP
description: The following analytic detects the execution of CompatTelRunner.exe with parameters indicative of a process not part of the normal "Microsoft Compatibility Appraiser" telemetry collection. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process names, parent processes, and command-line arguments. This activity is significant because CompatTelRunner.exe and the "Microsoft Compatibility Appraiser" task always run as System and can be used to elevate privileges or establish a highly privileged persistence mechanism. If confirmed malicious, this could enable unauthorized code execution, privilege escalation, or persistent access to the compromised system.
data_source:
    - Windows Event Log Security 4688
    - Sysmon EventID 1
    - CrowdStrike ProcessRollup2
search: |-
    | tstats `security_content_summariesonly` count min(_time) AS firstTime, max(_time) AS lastTime FROM datamodel=Endpoint.Processes
      WHERE Processes.parent_process_name = "CompatTelRunner.exe"
        AND
        Processes.process="* -cv:*" NOT Processes.process IN ("* -m:*")
      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_compatibility_telemetry_suspicious_child_process_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: No false positives have been identified at this time.
references:
    - https://attack.mitre.org/techniques/T1546/
    - https://scythe.io/threat-thursday/windows-telemetry-persistence
    - https://www.trustedsec.com/blog/abusing-windows-telemetry-for-persistence
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") starthoursago=168  | 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: $info_min_time$
      latest_offset: $info_max_time$
    - name: Investigate processes on $dest$
      search: '| from datamodel Endpoint.Processes | search dest = "$dest$" AND process_name = "$process_name$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
rba:
    message: The process $process_name$ was launched in a suspicious manner by $parent_process_name$ on host $dest$
    risk_objects:
        - field: dest
          type: system
          score: 50
    threat_objects:
        - field: process_name
          type: process
tags:
    analytic_story:
        - Windows Persistence Techniques
    asset_type: Endpoint
    mitre_attack_id:
        - T1546
        - T1053.005
    product:
        - Splunk Enterprise
        - Splunk Enterprise Security
        - Splunk Cloud
    security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1546/compattelrunner_abuse/compattelrunner_abuse.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog