Cracking Point-to-Point Tunneling Protocol (PPTP) encrypted VPN (1)

Cracking Point-to-Point Tunneling Protocol (PPTP) encrypted VPN (1)

PPTP (Point to Point Tunneling Protocol) is a Point-to-Point Tunneling Protocol. This protocol is a new enhanced security protocol developed on the basis of the PPP protocol. It supports multi-protocol Virtual Private Network (VPN) and can pass the password verification protocol (PAP) and Extensible Authentication Protocol (EAP) to enhance security. This allows remote users to access CEN through an ISP, a direct connection to the Internet, or other networks.

1. asleap + genkeys

The software used is the 'asleap + genkeys 'package. The parameters of the two software are very simple, and the actual use of the software will be depressing:

The process is: first capture the **. pcap file package containing the user name and password, then use genkeys to generate a dedicated asleap dictionary, and then use asleap to crack the captured package!

genkeys -r wordlist.lst -f wordlist.dat -n wordlist.idxasleap -r **.pcap -f wordlist.dat -n wordlist.idx

Asleap always reports the following error during actual use:

Finally found that foreign Daniel wrote a script, 'chap2asleap. py', turned over, according to the original article toss (original address: http://blog.g0tmi1k.com/2010/03/chap2asleappy-v011-vpn )!

First, the local machine starts arp spoofing on the target host:

arpspoof -i interface -t x.x.x.x y.y.y.yarpspoof -i interface -t y.y.y.y x.x.x.x

Next I started to use wireshark to capture packets (ps: I found that all the articles on the Internet "long ago" about pptp packet capture tools are anger and pptp-sniff. I haven't found any resources for a long time. I don't know why)

wireshark -i interface -k

Log on to the vpn on the target host, let wireshark capture the packet, and use 'chap 'to filter it out. Now we can see the plaintext user name, and copy the value values of Challenge and Response respectively:

 

 

Use 'chap2asleap. py' to crack the password:

python chap2asleap.py -C Challenge_value -R Response_value -x -v -d /path/to/wordlist.lst -p /path/to/asleap

-D # custom dictionary file, default/pentest/passwords/wordlists/darkc0de. lst

-P # specify the folder where asleap is located. Default Value:/usr/bin/

For example, if an error is reported for cracking a self-tested password, the attack in the video will be successful. It is estimated that the encryption protocol under win is enhanced.