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

From AIX 6.1 SECURITY TECHNICAL IMPLEMENTATION GUIDE

Associated with IA controls: ECSC-1

Associated with: CCI-000366

SV-40723r1_rule The 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

Check the SSH daemon configuration for the Compression setting. # grep -i Compression /etc/ssh/sshd_config | grep -v '^#' If the setting is present and set to "yes", this is a finding. If the setting is absent or set to "no" or "delayed", this is not a finding.

Fix text

Edit the /etc/ssh/sshd_config file and remove the Compression setting or set the Compression setting to "delayed" or "no".

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