Linux Kworker Process In Writable Process Path
Description
The following analytic detects the execution of a kworker process with a command line in writable directories such as /home/, /var/log, and /tmp on a Linux machine. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process and parent process paths. This activity is significant as kworker processes are typically kernel threads, and their presence in writable directories is unusual and indicative of potential malware, such as CyclopsBlink. If confirmed malicious, this could allow attackers to blend malicious processes with legitimate ones, leading to persistent access and further system compromise.
Query · spl
| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
WHERE Processes.parent_process = "*[kworker/*" Processes.parent_process_path IN ("/home/*", "/tmp/*", "/var/log/*") Processes.process="*iptables*"
BY Processes.action Processes.dest Processes.original_file_name
Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
Processes.process Processes.process_exec Processes.process_guid
Processes.process_hash Processes.process_id Processes.process_integrity_level
Processes.process_name Processes.process_path Processes.user
Processes.user_id Processes.vendor_product
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `linux_kworker_process_in_writable_process_path_filter`
Implementation guide
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
- No false positives have been identified at this time.
Analyst notes
Known false positives: No false positives have been identified at this time.