This rule is designed to detect the unauthorized removal of the immutable file attribute on a Linux system. The immutable attribute is a special file attribute in Linux that prevents files from being modified or deleted. By using the 'chattr' command with the '-i' option, users can remove this attribute. This activity can indicate potential malicious behavior, such as an attacker attempting to alter or delete sensitive files that are normally protected. The detection relies on system calls made through the 'EXECVE' function associated with the 'chattr' command. A medium alert level is set due to the potential for false positives, particularly when administrators need to interact with immutable files for legitimate purposes, such as maintenance or backups. It is essential to monitor these events closely to differentiate between legitimate administrative actions and potential malicious intent.