Title

The SSH daemon must restrict login ability to specific users and/or groups. (Cat II impact)

Discussion

Restricting SSH logins to a limited group of users, such as system administrators, prevents password-guessing and other SSH attacks from reaching system accounts and other accounts not authorized for SSH access.

Check Content

There are two ways in which access to SSH may restrict users or groups. Check if /etc/pam.d/sshd is configured to require daemon style login control. # grep pam_access.so /etc/pam.d/sshd|grep "required"|grep "account"| grep -v '^#' If no lines are returned, sshd is not configured to use pam_access. Check the SSH daemon configuration for the AllowGroups setting. # egrep -i "AllowGroups|AllowUsers" /etc/ssh/sshd_config | grep -v '^#' If no lines are returned, sshd is not configured to limit access to users/groups. If sshd is not configured to limit access either through pam_access or the use "AllowUsers" or "Allowgroups", this is a finding.

Fix Text

Edit the SSH daemon configuration and add an "AllowGroups" or "AllowUsers" directive. specifying the groups and users allowed to have access. Restart the SSH daemon. # /sbin/service sshd restart Alternatively, modify the /etc/pam.d/sshd file to include the line account required pam_access.so accessfile=<path to access.conf for sshd> If the "accessfile" option is not specified the default "access.conf" file will be used. The "access.conf" file must contain the user restriction definitions.

Additional Identifiers

Rule ID: SV-46033r2_rule

Vulnerability ID: V-22470

Group Title: GEN005521

Expert Comments

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