splApache-2.0from splunk/security_content

Linux Deletion Of Cron Jobs

The following analytic detects the deletion of cron jobs on a Linux machine. It leverages filesystem event logs to identify when files within the "/etc/cron.*" directory are deleted. This activity is significant because attackers or malware may delete cron jobs to disable scheduled security tasks or evade detection mechanisms. If confirmed malicious, this action could allow an attacker to disrupt system operations, evade security measures, or facilitate further malicious activities such as data wiping, as seen with the acidrain malware.

Quality

FP risk

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Forks

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Rule sourcedetections/endpoint/linux_deletion_of_cron_jobs.yml

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Filesystem
  WHERE Filesystem.action=deleted Filesystem.file_path="/etc/cron.*"
  BY Filesystem.action Filesystem.dest Filesystem.file_access_time
     Filesystem.file_create_time Filesystem.file_hash Filesystem.file_modify_time
     Filesystem.file_name Filesystem.file_path Filesystem.file_acl
     Filesystem.file_size Filesystem.process_guid Filesystem.process_id
     Filesystem.user Filesystem.vendor_product
| `drop_dm_object_name(Filesystem)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `linux_deletion_of_cron_jobs_filter`