Detection: Linux Indicator Removal Service File Deletion

Description

The following analytic detects the deletion of Linux service unit configuration files by suspicious processes. It leverages Endpoint Detection and Response (EDR) telemetry, focusing on processes executing the 'rm' command targeting '.service' files. This activity is significant as it may indicate malware attempting to disable critical services or security products, a common defense evasion tactic. If confirmed malicious, this behavior could lead to service disruption, security tool incapacitation, or complete system compromise, severely impacting the integrity and availability of the affected Linux host.

Search

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name = "rm"  AND Processes.process = "*rm *"  AND Processes.process = "*.service" by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id Processes.process_guid 
3| `drop_dm_object_name(Processes)` 
4| `security_content_ctime(firstTime)` 
5| `linux_indicator_removal_service_file_deletion_filter`

Data Source

Name	Platform	Sourcetype	Source
Sysmon for Linux EventID 1	Linux	'sysmon:linux'	'Syslog:Linux-Sysmon/Operational'

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

network admin can delete services unit configuration file as part of normal software installation. Filter is needed.

Associated Analytic Story

• AwfulShred

• Data Destruction

Risk Based Analytics (RBA)

References

• https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/overview-of-the-cyber-weapons-used-in-the-ukraine-russia-war/

• https://cert.gov.ua/article/3718487

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