Information
Ensure that system and security updates are installed after they are available from Apple. This setting enables definition updates for XProtect and Gatekeeper, with this setting in place new malware and adware that Apple has added to the list of malware or untrusted software will not execute. These updates do not require reboots or end user admin rights.
http://www.thesafemac.com/tag/xprotect/
https://support.apple.com/en-us/HT202491
Rationale:
Patches need to be applied in a timely manner to reduce the risk of vulnerabilities being exploited
Impact:
Unpatched software may be exploited
Solution
Perform the following to enable system data files and security updates to install automatically:
Graphical Method:
Open System Preferences
Select Software Updates
Select Advanced
Select Install system data files and security updates
Terminal Method:
Run the following commands to enable automatically checking of system data files and security updates:
$ sudo defaults write /Library/Preferences/com.apple.SoftwareUpdate ConfigDataInstall -bool true
$ sudo defaults write /Library/Preferences/com.apple.SoftwareUpdate CriticalUpdateInstall -bool true