Boot or Logon Initialization Scripts: Rc.common
Adversaries may use rc.common automatically executed at boot initialization to establish persistence. During the boot process, macOS executes
source /etc/rc.common, which is a shell script containing various utility functions. This file also defines routines for processing command-line arguments and for gathering system settings and is thus recommended to include in the start of Startup Item Scripts . In macOS and OS X, this is now a deprecated mechanism in favor of Launch Agent and Launch Daemon but is currently still used.
Adversaries can use the rc.common file as a way to hide code for persistence that will execute on each reboot as the root user. 
|Restrict File and Directory Permissions||
Limit privileges of user accounts so only authorized users can edit the rc.common file.
/etc/rc.common file can be monitored to detect changes from the company policy. Monitor process execution resulting from the rc.common script for unusual or unknown applications or behavior.