splApache-2.0from splunk/security_content

Rundll32 Shimcache Flush

The following analytic detects the execution of a suspicious rundll32 command line used to clear the shim cache. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process execution logs and command-line arguments. This activity is significant because clearing the shim cache is an anti-forensic technique aimed at evading detection and removing forensic artifacts. If confirmed malicious, this action could hinder incident response efforts, allowing an attacker to cover their tracks and maintain persistence on the compromised machine.

Quality

FP risk

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Forks

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Rule sourcedetections/endpoint/rundll32_shimcache_flush.yml

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
  WHERE `process_rundll32`
    AND
    Processes.process = "*apphelp.dll,ShimFlushCache*"
  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)`
| `rundll32_shimcache_flush_filter`