This detection rule aims to identify potential techniques for maintaining persistence in a Linux environment via the creation or modification of cron files. Cron is a time-based job scheduler that allows users to run scripts or commands at specified intervals. This rule triggers when cron files or directories that are commonly used to set up scheduled tasks are created or modified. These include various directories such as `/etc/cron.d/`, `/etc/cron.daily/`, `/etc/cron.hourly/`, and others that store cron job configurations. Additionally, it watches for changes in specific files like `/etc/cron.allow`, `/etc/cron.deny`, and `/etc/crontab`. The condition to trigger the detection requires that at least one of the defined selections matches, indicating potentially unauthorized alterations that could signal an attacker’s effort to establish persistence on the system. While this rule is effective, it does have a known false positive for legitimate cron file creations, which administrators must account for during investigations.