The SUSE operating system SSH daemon must not allow compression or must only allow compression after successful authentication.

From SLES 12 Security Technical Implementation Guide

Associated with: CCI-000366

SV-92167r2_rule The SUSE operating system SSH daemon must not allow compression or must only allow compression after successful authentication.

Vulnerability discussion

If compression is allowed in an SSH connection prior to authentication, vulnerabilities in the compression software could result in compromise of the system from an unauthenticated connection, potentially with root privileges.

Check content

Verify the SUSE operating system SSH daemon performs compression after a user successfully authenticates. Check that the SSH daemon performs compression after a user successfully authenticates with the following command: # sudo grep -i compression /etc/ssh/sshd_config Compression delayed If the "Compression" keyword is set to "yes", is missing, or the returned line is commented out, this is a finding.

Fix text

Configure the SUSE operating system SSH daemon performs compression after a user successfully authenticates. Uncomment the "Compression" keyword in "/etc/ssh/sshd_config" on the system and set the value to "delayed" or "no": Compression no

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