The Juniper SRX Services Gateway must implement replay-resistant authentication mechanisms for network access to privileged accounts.

A replay attack may enable an unauthorized user to gain access to the application. Authentication sessions between the authenticator and the application 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.

There are 2 approved methods for accessing the Juniper SRX which are, in order of preference, the SSH protocol and the console port.

Verify SSH is configured to use a replay-resistant authentication mechanism.

[edit] show system services ssh

If SSH is not configured to use the MAC authentication protocol, this is a finding.

Configure SSH to use a replay-resistant authentication mechanism. The following is an example stanza.

[edit] set system services ssh macs hmac-sha2-512 set system services ssh macs hmac-sha2-256 set system services ssh macs hmac-sha1 set system services ssh macs hmac-sha1-96