V-240486

Discussion

Without cryptographic integrity protections, information can be altered by unauthorized users without detection. Remote access (e.g., RDP) is access to DoD nonpublic information systems by an authorized user (or an information system) communicating through an external, non-organization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless. Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the secret key used to generate the hash.

Check Content

Check the SSH daemon configuration for DoD-approved encryption to protect the confidentiality of SSH remote connections by performing the following commands:

Check the "Ciphers" setting in the "sshd_config" file.

# grep -i Ciphers /etc/ssh/sshd_config  | grep -v '#' 

The output must contain either nothing or any number of the following algorithms:

aes128-ctr, aes256-ctr.

If the output contains an algorithm not listed above, this is a finding.

Expected Output:
Ciphers aes256-ctr,aes128-ctr