A weakness has been reported in certain Cisco products, which can be exploited by malicious people to gain knowledge of certain information.

The problem is that the device returns different responses depending on whether or not a valid group name is supplied when the device is configured for group name authentication and using a pre-shared key.

Once a valid group name is guessed, this can further be used to obtain the hash of the group password.

The following products are affected:
* Cisco VPN 3000 Series Concentrators (models 3005, 3015, 3020, 3030, 3060, and 3080).
* Cisco PIX 500 Series Security Appliances
* Cisco ASA 5500 Series Adaptive Security Appliances

Solution
Update to a fixed version.
Further details available to Secunia VIM customers

Provided and/or discovered by
Roy Hills, NTA Monitor.

Changelog
Further details available to Secunia VIM customers

Original Advisory
NTA Monitor:
http://www.nta-monitor.com/news/vpn-flaws/cisco/VPN-Concentrator/index.htm

Cisco:
http://www.cisco.com/warp/public/707/cisco-sn-20050624-vpn-grpname.shtml
http://www.cisco.com/univercd/cc/td/doc/product/vpn/vpn3000/4_7/471con3k.htm

Deep Links
Links available to Secunia VIM customers