The macOS system must be configured with the SSH daemon LoginGraceTime set to 30 or less.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-81655	AOSX-13-000722	SV-96369r1_rule		Medium

Description
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.

Description

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.

STIG	Date
Apple OS X 10.13 Security Technical Implementation Guide	2019-03-08

Details

Check Text ( C-81431r1_chk )
The SSH daemon "LoginGraceTime" must be set correctly. To check the amount of time that a user can log on through SSH, run the following command: /usr/bin/sudo /usr/bin/grep ^LoginGraceTime /etc/ssh/sshd_config If the value is not set to "30" or less, this is a finding.

Fix Text (F-88503r1_fix)
To ensure that "LoginGraceTime" is configured correctly, run the following command: /usr/bin/sudo /usr/bin/sed -i.bak 's/.LoginGraceTime./LoginGraceTime 30/' /etc/ssh/sshd_config