Vulnerability Discussion

A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not log out because of the temporary nature of the absence. Rather than relying on the user to lock their operating system session manually prior to leaving the workstation, operating systems must be able to identify when a user's session has idled, and take action to initiate the session lock.

The session lock is implemented at the point where session activity can be determined and/or controlled.

Check

Verify the operating system initiates a session lock a for graphical user interfaces when the screensaver is activated.

Note: If the system does not have GNOME installed, this requirement is Not Applicable. The screen program must be installed to lock sessions on the console.

If GNOME is installed, check to see a session lock occurs when the screensaver is activated with the following command:

# grep -i lock-delay /etc/dconf/db/local.d/*
lock-delay=uint32 5

If the "lock-delay" setting is missing, or is not set to "5" or less, this is a finding.

Fix

Configure the operating system to initiate a session lock for graphical user interfaces when a screensaver is activated.

Create a database to contain the system-wide screensaver settings (if it does not already exist) with the following command:

# touch /etc/dconf/db/local.d/00-screensaver

Add the setting to enable session locking when a screensaver is activated:

[org/gnome/desktop/screensaver]
lock-delay=uint32 5

The "uint32" must be included along with the integer key values as shown.

Update the system databases:

# dconf update

Users must log out and then log in again before the system-wide settings take effect.