Breaking Microsoft's PPTP Protocol
Some things never change. Thirteen years ago, Mudge and I published a paper breaking Microsoft’s PPTP protocol and the MS-CHAP authentication system. I haven’t been paying attention, but I presume it’s been fixed and improved over the years. Well, it’s been broken again.
ChapCrack can take captured network traffic that contains a MS-CHAPv2 network handshake (PPTP VPN or WPA2 Enterprise handshake) and reduce the handshake’s security to a single DES (Data Encryption Standard) key.
This DES key can then be submitted to CloudCracker.com—a commercial online password cracking service that runs on a special FPGA cracking box developed by David Hulton of Pico Computing—where it will be decrypted in under a day.
The CloudCracker output can then be used with ChapCrack to decrypt an entire session captured with WireShark or other similar network sniffing tools.