Symantec Firewall/VPN Appliance 100 through 200R hardcodes the administrator's MAC address inside the firewall's configuration, which allows remote attackers to spoof the administrator's MAC address and perform an ARP poisoning man-in-the-middle attack to obtain the administrator's password.
http://www.iss.net/security_center/static/10442.php
http://archives.neohapsis.com/archives/bugtraq/2002-10/0329.html
http://archives.neohapsis.com/archives/bugtraq/2002-10/0314.html