The macOS system must disable login to other users' active and locked sessions.

The ability to log in to another user's active or locked session must be disabled. macOS has a privilege that can be granted to any user that will allow that user to unlock active users' sessions. Disabling the administrator's and/or user's ability to log in to another user's active and locked session prevents unauthorized people from viewing potentially sensitive and/or personal information. NOTE: Configuring this setting will change the user experience and disable TouchID from unlocking the screen saver. To restore the user experience and allow TouchID to unlock the screen saver, run "/usr/bin/sudo /usr/bin/defaults write /Library/Preferences/com.apple.loginwindow screenUnlockMode -int 1". This setting can also be deployed with a configuration profile. Satisfies: SRG-OS-000104-GPOS-00051, SRG-OS-000109-GPOS-00056