Cisco VPN Client on Windows before 4.8.02.0010 allows local users to gain privileges by enabling the "Start Before Logon" (SBL) and Microsoft Dial-Up Networking options, and then interacting with the dial-up networking dialog box.
https://exchange.xforce.ibmcloud.com/vulnerabilities/36029
http://www.vupen.com/english/advisories/2007/2903
http://www.securityfocus.com/bid/25332
http://www.cisco.com/warp/public/707/cisco-sa-20070815-vpnclient.shtml