AlmaLinux OS 9 must terminate idle user sessions.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-269421	SRG-OS-000163-GPOS-00072	ALMA-09-040500	SV-269421r1050304_rule	2025-02-20	1

Description
Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended. In addition, quickly terminating an idle session will also free up resources committed by the managed network element. Terminating network connections associated with communications sessions includes, for example, de-allocating associated TCP/IP address/port pairs at the operating system level, and de-allocating networking assignments at the application level if multiple application sessions are using a single operating system-level network connection. This does not mean that the operating system terminates all sessions or network access; it only ends the inactive session and releases the resources associated with that session.

Description

Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended. In addition, quickly terminating an idle session will also free up resources committed by the managed network element. Terminating network connections associated with communications sessions includes, for example, de-allocating associated TCP/IP address/port pairs at the operating system level, and de-allocating networking assignments at the application level if multiple application sessions are using a single operating system-level network connection. This does not mean that the operating system terminates all sessions or network access; it only ends the inactive session and releases the resources associated with that session.

ℹ️ Check
Verify that AlmaLinux OS 9 logs out sessions that are idle for 15 minutes with the following command: $ systemd-analyze cat-config systemd/logind.conf \| grep StopIdleSessionSec #StopIdleSessionSec=infinity StopIdleSessionSec=900 If "StopIdleSessionSec" is not configured to "900" seconds, this is a finding.

✔️ Fix
Configure AlmaLinux OS 9 to log out idle sessions. Create the directory if necessary: $ mkdir -p /etc/systemd/logind.conf.d/ Create a *.conf file in /etc/systemd/logind.conf.d/ with the following content: [Login] StopIdleSessionSec=900 KillUserProcesses=no Restart systemd-logind: $ systemctl restart systemd-logind