RapidStream offers a line of VPN/Firewall network devices. Each product comes with a modified version of sshd for encrypted remote administration. This version of sshd has a "hard-coded" username in it, rsadmin with a null password (rsadmin = root). The authentication was to be done by the RapidStream remote administration software, above the OS level. Unfortunately, it is possible to execute commands on the target RapidStream device in the *sh manner (from the Bugtraq post):
[root@attacker]# ssh -l rsadmin <ip of vpn> "/bin/sh -i;"
The commands-to-execute argument causes sshd to circumvent execution of the remote administration utility (which is hardcoded in for rsadmin) and execute the commands specified as root. Exploitation of this can result in a complete remote compromise of your RapidStream VPN devices or Firewalls.
RapidStream is reportedly correcting the modified sshd in their product.