Linux Add Files In Known Crontab Directories
The following analytic detects unauthorized file creation in known crontab directories on Unix-based systems. It leverages filesystem data to identify new files in directories such as /etc/cron* and…
Description
The following analytic detects unauthorized file creation in known crontab directories on Unix-based systems. It leverages filesystem data to identify new files in directories such as /etc/cron* and /var/spool/cron/*. This activity is significant as it may indicate an attempt by threat actors or malware to establish persistence on a compromised host. If confirmed malicious, this could allow attackers to execute arbitrary code at scheduled intervals, potentially leading to further system compromise and unauthorized access to sensitive information.
Detection logic
Detection requirements
- Platform
- ESXiLinuxmacOS
The rule states no platform. This is derived from the ATT&CK technique it maps to.
- Log source category
- sysmon_for_linux_eventid_11
Known benign triggers
- Administrator or network operator can create file in crontab folders for automation purposes. Please update the filter macros to remove false positives.
MITRE ATT&CK mappings
0 exclusive techniques.This is coverage no other published rule has; it is not this rule's total technique count.
References
| Reference | Cited by |
|---|---|
| www.cyberciti.biz/faq/how-do-i-add-jobs-to-cron-under-linux-or-unix-oses/ | Only this detection cites it |
| www.sandflysecurity.com/blog/detecting-cronrat-malware-on-linux-instantly/ | Only this detection cites it |
From the source
- At source
- Open at source
- Upstream identifier
- 023f3452-5f27-11ec-bf00-acde48001122
- Tagged by the source as
- Linux Living Off The LandLinux Persistence TechniquesLinux Privilege EscalationScheduled TasksXorDDosEndpointendpointSplunk CloudSplunk EnterpriseSplunk Enterprise Securityendpoint
Licence
- Published under
- Apache License 2.0Read the licence
- Attribution
- Required
- Obtained under
- Apache-2.0Read the origin licence
Authorship
- Written by
- Published
- Aug 26, 2026
- Version
- 1