Information
The guest account allows users access to the system without having to create an account or password. Guest users are unable to make setting changes, cannot remotely login to the system and all created files, caches, and passwords are deleted upon logging out.
Rationale:
Disabling the guest account mitigates the risk of an untrusted user doing basic reconnaissance and possibly using privilege escalation attacks to take control of the system.
Impact:
A guest user can use that access to find out additional information about the system and might be able to use privilege escalation vulnerabilities to establish greater access.
Solution
Perform the following to disable guest account availability:
Graphical Method:
Open System Preferences
Select Users & Groups
Select Guest User
Uncheck Allow guests to log in to this computer
Terminal Method:
Run the following command to disable the guest account:
$ sudo defaults write /Library/Preferences/com.apple.loginwindow GuestEnabled -bool false
Additional Information:
By default, the guest account is enabled for access to sharing services, but is not allowed to log in to the computer.
The guest account does not need a password when it is enabled to log in to the computer.