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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-217279	SLES-12-030250	SV-217279r880925_rule		Medium

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.

STIG	Date
SLES 12 Security Technical Implementation Guide	2023-03-06

Details

Check Text ( C-18507r880923_chk )
Note: If the installed version of OpenSSH is 7.4 or above, this requirement is not applicable. 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.

Check Text ( C-18507r880923_chk )

Note: If the installed version of OpenSSH is 7.4 or above, this requirement is not applicable.

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 (F-18505r880924_fix)
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