Detection: Excessive Usage Of Taskkill

Description

The following analytic identifies excessive usage of taskkill.exe, a command-line utility used to terminate processes. The detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on instances where taskkill.exe is executed ten or more times within a one-minute span. This behavior is significant as adversaries often use taskkill.exe to disable security tools or other critical processes to evade detection. If confirmed malicious, this activity could allow attackers to bypass security defenses, maintain persistence, and further compromise the system.

Search

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime values(Processes.action) as action values(Processes.dest) as dest values(Processes.original_file_name) as original_file_name values(Processes.parent_process) as parent_process values(Processes.parent_process_exec) as parent_process_exec values(Processes.parent_process_guid) as parent_process_guid values(Processes.parent_process_id) as parent_process_id values(Processes.parent_process_path) as parent_process_path values(Processes.process) as process values(Processes.process_exec) as process_exec values(Processes.process_guid) as process_guid values(Processes.process_hash) as process_hash values(Processes.process_id) as process_id values(Processes.process_integrity_level) as process_integrity_level values(Processes.process_path) as process_path values(Processes.user) as user  values(Processes.user_id) as user_id values(Processes.vendor_product) as vendor_product from datamodel=Endpoint.Processes where Processes.process_name = "taskkill.exe" by Processes.parent_process_name Processes.process_name Processes.dest Processes.user _time span=1m 
3| where count >=10 
4| `drop_dm_object_name(Processes)` 
5| `security_content_ctime(firstTime)` 
6| `security_content_ctime(lastTime)` 
7| `excessive_usage_of_taskkill_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	N/A	'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

Unknown. Filter as needed.

Associated Analytic Story

• AgentTesla

• Azorult

• CISA AA22-264A

• CISA AA22-277A

• Crypto Stealer

• NjRAT

• XMRig

Risk Based Analytics (RBA)

Risk Message:

Excessive usage of taskkill.exe with process id $process_id$ (more than 10 within 1m) has been detected on $dest$ with a parent process of $parent_process_name$.

References

• https://thedfirreport.com/2020/04/20/sqlserver-or-the-miner-in-the-basement/

• https://www.joesandbox.com/analysis/702680/0/html

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: 8