Detection: Windows Compatibility Telemetry Suspicious Child Process

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.

Search

 1
 2|  tstats `security_content_summariesonly` values(Processes.parent_process) as Processes.parent_process, values(Processes.process) as Processes.process values(Processes.process_current_directory) AS process_current_directory, values(Processes.process_id) as Processes.process_id, values(Processes.process_guid) as Processes.process_guid, 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 _time span=1h Processes.user Processes.dest Processes.parent_process_name Processes.process_name
 3
 4|`drop_dm_object_name(Processes)`
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 6| `security_content_ctime(firstTime)` 
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 8| `security_content_ctime(lastTime)`
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10| `windows_compatibility_telemetry_suspicious_child_process_filter`

Data Source

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

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

None identified

Associated Analytic Story

• Windows Persistence Techniques

Risk Based Analytics (RBA)

Risk Message:

The process $process_name$ was launched in a suspicious manner by $parent_process_name$ on host $dest$

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

Detection Testing

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 1