Windows Compatibility Telemetry Tampering Through Registry

name: Windows Compatibility Telemetry Tampering Through Registry
id: 43834687-cc48-4878-a2fa-f76e4271791f
version: 9
creation_date: '2025-02-13'
modification_date: '2026-05-13'
author: Steven Dick
status: production
type: TTP
description: This detection identifies suspicious modifications to the Windows Compatibility Telemetry registry settings, specifically within the "TelemetryController" registry key and "Command" registry value. It leverages data from the Endpoint.Registry data model, focusing on registry paths and values indicative of such changes. 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:
    - Sysmon EventID 13
search: |-
    | tstats `security_content_summariesonly` min(_time) as firstTime, max(_time) as lastTime, count FROM datamodel=Endpoint.Registry
      WHERE (
            Registry.registry_path = "*\\SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\AppCompatFlags\\TelemetryController*"
            AND
            Registry.registry_value_name="Command" NOT Registry.registry_value_data IN ("(empty)")
        )
      BY Registry.action Registry.dest Registry.process_guid
         Registry.process_id Registry.registry_hive Registry.registry_path
         Registry.registry_key_name Registry.registry_value_data Registry.registry_value_name
         Registry.registry_value_type Registry.status Registry.user
         Registry.vendor_product
    | `drop_dm_object_name(Registry)`
    | eval process = registry_value_data
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `windows_compatibility_telemetry_tampering_through_registry_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 - "$dest$" and "$user$"
      search: '%original_detection_search% | search dest = "$dest$" user = "$user$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$" and "$user$"
      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"
    - name: Investigate registry changes on $dest$
      search: '| from datamodel Endpoint.Registry | search registry_path = "*\\SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\AppCompatFlags\\TelemetryController*" AND dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
finding:
    title: The process $process$ was added to registry settings for the Compatibility Appraiser by $user$ on host $dest$
    entity:
        field: user
        type: user
        score: 50
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 50
          message: The process $process$ was added to registry settings for the Compatibility Appraiser by $user$ on host $dest$
threat_objects:
    - field: process
      type: process
analytic_story:
    - Windows Persistence Techniques
asset_type: Endpoint
mitre_attack_id:
    - T1546
    - T1053.005
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/T1546/compattelrunner_abuse/compattelrunner_abuse.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit