Check: SLES-12-030170
SLES 12 STIG:
SLES-12-030170
(in versions v2 r13 through v2 r2)
Title
The SUSE operating system must implement DoD-approved encryption to protect the confidentiality of SSH remote connections. (Cat II impact)
Discussion
Without confidentiality protection mechanisms, unauthorized individuals may gain access to sensitive information via a remote access session. Remote access is access to DoD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless. Encryption provides a means to secure the remote connection to prevent unauthorized access to the data traversing the remote access connection (e.g., RDP), thereby providing a degree of confidentiality. The encryption strength of a mechanism is selected based on the security categorization of the information. The system will attempt to use the first cipher presented by the client that matches the server list. Listing the values "strongest to weakest" is a method to ensure the use of the strongest cipher available to secure the SSH connection. Satisfies: SRG-OS-000033-GPOS-00014, SRG-OS-000120-GPOS-00061, SRG-OS-000125-GPOS-00065, SRG-OS-000250-GPOS-00093, SRG-OS-000393-GPOS-00173
Check Content
Verify that the SUSE operating system implements DoD-approved encryption to protect the confidentiality of SSH remote connections. Check the SSH daemon configuration for allowed ciphers with the following command: # sudo grep -i ciphers /etc/ssh/sshd_config | grep -v '^#' Ciphers aes256-ctr,aes192-ctr,aes128-ctr If any ciphers other than "aes256-ctr", "aes192-ctr", or "aes128-ctr" are listed, the order differs from the example above, the "Ciphers" keyword is missing, or the returned line is commented out, this is a finding.
Fix Text
Edit the SSH daemon configuration (/etc/ssh/sshd_config) and remove any ciphers not starting with "aes" and remove any ciphers ending with "cbc". If necessary, add a "Ciphers" line: Ciphers aes256-ctr,aes192-ctr,aes128-ctr Restart the SSH daemon: # sudo systemctl restart sshd.service
Additional Identifiers
Rule ID: SV-217270r877398_rule
Vulnerability ID: V-217270
Group Title: SRG-OS-000033-GPOS-00014
Expert Comments
CCIs
| Number | Definition |
|---|---|
| CCI-000068 |
The information system implements cryptographic mechanisms to protect the confidentiality of remote access sessions. |
| CCI-000366 |
The organization implements the security configuration settings. |
| CCI-000803 |
The information system implements mechanisms for authentication to a cryptographic module that meet the requirements of applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance for such authentication. |
| CCI-002890 |
The information system implements cryptographic mechanisms to protect the integrity of nonlocal maintenance and diagnostic communications. |