Vulnerability Discussion

A session 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 want to log out because of the temporary nature of the absence.

The session lock is implemented at the point where session activity can be determined. Rather than be forced to wait for a period of time to expire before the user session can be locked, RHEL 8 needs to provide users with the ability to manually invoke a session lock so users can secure their session if it is necessary to temporarily vacate the immediate physical vicinity.

Tmux is a terminal multiplexer that enables a number of terminals to be created, accessed, and controlled from a single screen. Red Hat endorses tmux as the recommended session controlling package.

Satisfies: SRG-OS-000029-GPOS-00010, SRG-OS-000031-GPOS-00012

Check

Verify the operating system initiates a session lock after a 15-minute period of inactivity for graphical user interfaces with the following commands:

$ sudo gsettings get org.gnome.desktop.session idle-delay

uint32 900

If "idle-delay" is set to "0" or a value greater than "900", this is a finding.

Note: This requirement assumes the use of the RHEL 8 default graphical user interface, Gnome Shell. If the system does not have any graphical user interface installed, this requirement is Not Applicable.

Fix

Configure the operating system to initiate a screensaver after a 15-minute period of inactivity for graphical user interfaces.

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

$ sudo touch /etc/dconf/db/local.d/00-screensaver

Edit /etc/dconf/db/local.d/00-screensaver and add or update the following lines:

[org/gnome/desktop/session]
# Set the lock time out to 900 seconds before the session is considered idle
idle-delay=uint32 900

Update the system databases:

$ sudo dconf update