An OpenSSH daemon listens on TCP port 22. There is a hard-coded entry in the /etc/shadow file in the firmware image for the root user. However, in the default SSH configuration the PermitRootLogin is disabled, preventing the root user from logging in via SSH. This configuration can be bypassed/changed by an attacker through multiple paths though.
The product contains functionality that is not documented, not part of the specification, and not accessible through an interface or command sequence that is obvious to the product’s users or administrators.