Detection: Splunk Command and Scripting Interpreter Risky Commands

Description

The following analytic identifies the execution of risky commands within the Splunk platform, such as runshellscript, delete, and sendemail. It leverages the Search_Activity data model to detect ad hoc searches containing these commands, excluding those run by the splunk-system-user. This activity is significant because it may indicate attempts at data exfiltration, deletion, or other unauthorized actions by a malicious user. If confirmed malicious, this could lead to data loss, unauthorized data transfer, or system compromise, severely impacting the organization's security posture.

Search

 1
 2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Splunk_Audit.Search_Activity where Search_Activity.search IN ("*
 3| runshellscript *", "*
 4| collect *","*
 5| delete *", "*
 6| fit *", "*
 7| outputcsv *", "*
 8| outputlookup *", "*
 9| run *", "*
10| script *", "*
11| sendalert *", "*
12| sendemail *", "*
13| tscolle*") Search_Activity.search_type=adhoc Search_Activity.user!=splunk-system-user by Search_Activity.search Search_Activity.info Search_Activity.total_run_time Search_Activity.user Search_Activity.search_type 
14| `drop_dm_object_name(Search_Activity)` 
15| `security_content_ctime(firstTime)` 
16| `security_content_ctime(lastTime)` 
17| `splunk_command_and_scripting_interpreter_risky_commands_filter`

Data Source

Name	Platform	Sourcetype	Source
Splunk	Splunk	'splunkd_ui_access'	'splunkd_ui_access.log'

Macros Used

Annotations

Default Configuration

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

Implementation

To successfully implement this search acceleration is recommended against the Search_Activity datamodel that runs against the splunk _audit index. In addition, this analytic requires the Common Information Model App which includes the Splunk Audit Datamodel https://splunkbase.splunk.com/app/1621/. Splunk SOAR customers can find a SOAR workbook that walks an analyst through the process of running these hunting searches in the references list of this detection. In order to use this workbook, a user will need to run a curl command to post the file to their SOAR instance such as "curl -u username:password https://soar.instance.name/rest/rest/workbook_template -d @splunk_psa_0622.json". A user should then create an empty container or case, attach the workbook, and begin working through the tasks.

Known False Positives

False positives will be present until properly filtered by Username and search name.

Associated Analytic Story

• Splunk Vulnerabilities

Risk Based Analytics (RBA)

References

• https://docs.splunk.com/Documentation/Splunk/latest/Security/SPLsafeguards#Commands_that_trigger_the_warning

• https://www.github.com/splunk/security_content/blob/develop/workbooks/splunk_psa_0622.json

• https://advisory.splunk.com/advisories/SVD-2024-0302

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: 3