This detection rule, crafted by Elastic, focuses on monitoring syslog logs for error messages pertaining to the rc.local process on Linux systems. The rc.local file is meant to execute commands at system startup. However, it's a potential target for attackers aiming to introduce malicious scripts for persistence. The rule triggers on error messages such as 'Connection refused', 'No such file or directory', and 'command not found', which could indicate illicit alterations made to the rc.local file. By regularly monitoring these logs, administrators can detect early signs of tampering and take preventive actions to secure the system from persistent threats.