Linux Indicator Removal Clear Cache
This analytic looks for processes that clear or free page cache in Linux system host. This technique was seen in Awfulshred malware wiper that tries to clear the cache using kernel system request drop_caches while wiping all files in the targeted host. This TTP detection can be a good indicator of user or process tries to clear page cache to delete tracks or might be a wiper like Awfulshred.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2023-02-09
- Author: Teoderick Contreras, Splunk
- ID: e0940505-0b73-4719-84e6-cb94c44a5245
Kill Chain Phase
- CIS 3
- CIS 5
- CIS 16
1 2 3 4 5 | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name IN ("dash", "sudo", "bash") AND Processes.process IN("* echo 3 > *", "* echo 2 > *","* echo 1 > *") AND Processes.process = "*/proc/sys/vm/drop_caches" by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id Processes.process_guid | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `linux_indicator_removal_clear_cache_filter`
The SPL above uses the following Macros:
linux_indicator_removal_clear_cache_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
Associated Analytic Story
|49.0||70||70||a $process_name$ clear cache using kernel drop cache system request in $dest$|
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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source | version: 1