Title

The macOS system must be configured with the SSH daemon ClientAliveInterval option set to 900 or less. (Cat II impact)

Discussion

SSH should be configured to log users out after a 15-minute interval of inactivity and to wait only 30 seconds before timing out logon attempts. 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 or an incomplete logon attempt will also free up resources committed by the managed network element.

Check Content

If SSH is not being used, this is Not Applicable. The SSH daemon "ClientAliveInterval" option must be set correctly. To check the idle timeout setting for SSH sessions, run the following: /usr/bin/grep ^ClientAliveInterval /etc/ssh/sshd_config If the setting is not "900" or less, this is a finding.

Fix Text

To ensure that "ClientAliveInterval" is set correctly, run the following command: /usr/bin/sudo /usr/bin/sed -i.bak 's/.*ClientAliveInterval.*/ClientAliveInterval 900/' /etc/ssh/sshd_config

Additional Identifiers

Rule ID: SV-230764r808494_rule

Vulnerability ID: V-230764

Group Title: SRG-OS-000163-GPOS-00072

Expert Comments

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