The SSH daemon must perform strict mode checking of home directory configuration files.

From Canonical Ubuntu 16.04 Security Technical Implementation Guide

Associated with: CCI-000366

SV-90527r2_rule The SSH daemon must perform strict mode checking of home directory configuration files.

Vulnerability discussion

If other users have access to modify user-specific SSH configuration files, they may be able to log on to the system as another user.

Check content

Verify the SSH daemon performs strict mode checking of home directory configuration files. Check that the SSH daemon performs strict mode checking of home directory configuration files with the following command: # grep StrictModes /etc/ssh/sshd_config StrictModes yes If "StrictModes" is set to "no", is missing, or the returned line is commented out, this is a finding.

Fix text

Configure SSH to perform strict mode checking of home directory configuration files. Uncomment the "StrictModes" keyword in "/etc/ssh/sshd_config" and set the value to "yes": StrictModes yes The SSH daemon must be restarted for the changes to take effect. To restart the SSH daemon, run the following command: # sudo systemctl restart sshd.service

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