Title

The operating system must implement replay-resistant authentication mechanisms for network access. (Cat II impact)

Discussion

A replay attack may enable an unauthorized user to gain access to the operating system. Authentication sessions between the authenticator and the operating system validating the user credentials must not be vulnerable to a replay attack. An authentication process resists replay attacks if it is impractical to achieve a successful authentication by recording and replaying a previous authentication message. Techniques used to address this include protocols using nonces (e.g., numbers generated for a specific one-time use) or challenges (e.g., TLS, WS_Security). Additional techniques include time-synchronous or challenge-response one-time authenticators. Satisfies: SRG-OS-000112-GPOS-00057, SRG-OS-000113-GPOS-00058

Check Content

Verify the operating system implements replay-resistant authentication mechanisms for network access. If it does not, this is a finding. # grep -i protocol /etc/ssh/sshd_config The returned line should indicate Protocol 2 is in use. If the returned line allows for use of Protocol 1, is commented out, or the line is missing, this is a finding.

Fix Text

Configure the operating system to implement replay-resistant authentication mechanisms for network access.

Additional Identifiers

Rule ID:

Vulnerability ID: V-570

Group Title:

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.