Detection: Windows MpCmdRun RemoveDefinitions Execution

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.

Search

 1
 2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime
 3  from datamodel=Endpoint.Processes where
 4  (Processes.process_name ="MpCmdRun.exe" OR Processes.original_file_name = MpCmdRun.exe)
 5  Processes.process = "*-RemoveDefinitions *"
 6  by Processes.action Processes.dest Processes.original_file_name Processes.parent_process
 7     Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id
 8     Processes.parent_process_name Processes.parent_process_path Processes.process Processes.process_exec
 9     Processes.process_guid Processes.process_hash Processes.process_id Processes.process_integrity_level
10     Processes.process_name Processes.process_path Processes.user Processes.user_id Processes.vendor_product
11
12| `drop_dm_object_name(Processes)`
13
14| `security_content_ctime(firstTime)`
15
16| `security_content_ctime(lastTime)`
17
18| `windows_mpcmdrun_removedefinitions_execution_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	Other	'crowdstrike:events:sensor'	'crowdstrike'
Sysmon EventID 1	Windows	'XmlWinEventLog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Windows Event Log Security 4688	Windows	'XmlWinEventLog'	'XmlWinEventLog:Security'

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

Administrators may execute this command for testing or auditing.

Associated Analytic Story

• BlankGrabber Stealer

Risk Based Analytics (RBA)

Risk Message:

An instance of [$process_name$] attempting to remove definitions from the Windows Malware Protection Engine via the Command [$process$] on [$dest$] by user [$user$].

References

• https://cert.gov.ua/article/6284730

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