Linux Shred Overwrite Command
This analytic is to detect a shred process to overwrite a files in a linux machine. Shred Linux application is designed to overwrite file to hide its contents or make the deleted file un-recoverable. Weve seen this technique in industroyer2 malware that tries to wipe energy facilities of targeted sector as part of its destructive attack. It might be some normal user may use this command for valid purposes but it is recommended to check what files, disk or folder it tries to shred that might be good pivot for incident response in this type of destructive malware.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2023-04-14
- Author: Teoderick Contreras, Splunk
- ID: c1952cf1-643c-4965-82de-11c067cbae76
Kill Chain Phase
- Actions On Objectives
- CIS 10
1 2 3 4 5 6 | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name =shred AND Processes.process IN ("*-n*", "*-u*", "*-z*", "*-s*") by Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id Processes.process_guid Processes.dest Processes.user | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `linux_shred_overwrite_command_filter`
The SPL above uses the following Macros:
linux_shred_overwrite_command_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
How To Implement
To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line executions from your endpoints. If you are using Sysmon, you can use the Add-on for Linux Sysmon from Splunkbase.
Known False Positives
Administrator or network operator can use this application for automation purposes. Please update the filter macros to remove false positives.
Associated Analytic Story
|49.0||70||70||A possible shred overwrite command $process$ executed on $dest$|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
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