The TOSS SSH daemon must not allow compression or must only allow compression after successful authentication.
Severity | Group ID | Group Title | Version | Rule ID | Date | STIG Version |
|---|---|---|---|---|---|---|
| medium | V-252943 | SRG-OS-000480-GPOS-00227 | TOSS-04-010410 | SV-252943r991589_rule | 2024-05-30 | 2 |
| Description |
|---|
| 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. |
| ℹ️ Check |
|---|
| Verify 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 |
|---|
| Uncomment the "Compression" keyword in "/etc/ssh/sshd_config" (this file may be named differently or be in a different location if using a version of SSH that is provided by a third-party vendor) on the system and set the value to "delayed" or "no": Compression no The SSH service must be restarted for changes to take effect. |