directly from the ISC
Moxie Marlinspike and David Hulton gave a talk at Defcon 20 on a presentation on cracking MS-CHAPv2 with 100% success rate. This protocol is still very much in use with PPTP VPNs, and WPA2 Enterprise environments for authentication.
Moxie's recommendations :
1- All users and providers of PPTP VPN solutions should immediately start migrating to a different VPN protocol. PPTP traffic should be considered unencrypted.
2- Enterprises who are depending on the mutual authentication properties of MS-CHAPv2 for connection to their WPA2 Radius servers should immediately start migrating to something else.
Knowing that MS-CHAPv2 can now be cracked, what alternatives are you considering to secure your now insecure communications? The two alternatives suggested by Moxie are "[...] OpenVPN configuration, or IPSEC in certificate rather than PSK mode."
 https://www.cloudcracker.com/blog/2012/ ... s-chap-v2/