The Downloadable RADIUS ACLs feature in Cisco PIX and VPN 3000 concentrators, when creating an ACL on the Cisco Secure Access Control Server (CS ACS), generates a random internal name for an ACL that is also used as a hidden user name and password, which allows remote attackers to gain privileges by sniffing the username from the cleartext portion of a RADIUS session, then using the password to log in to another device that uses CS ACS.
http://www.securityfocus.com/bid/16025
http://www.securityfocus.com/archive/1/420103/100/0/threaded
http://www.securityfocus.com/archive/1/420020/100/0/threaded
http://www.cisco.com/en/US/products/sw/secursw/ps2086/products_field_notice09186a00805bf1c4.shtml