This tutorial will require the use of Backtrack, get the latest version HERE and it is free.
Wireless technology comes at the price of security but at least WPA and WPA2 are safe right? Wrong. WPA and WPA2 are both crackable but the time it takes to crack depends on the strength of their password.
-Boot into BackTrack
-Open up Konsole which is a command line utility built into BackTrack. It is the Black Box in the Lower-Left Hand Corner (See Image).
-The following commands stop the wireless interface so you can change your mac address, this is important because your mac address is a unique identifier so faking one is a good idea if you are accessing a network you don’t have permission to. (Which by the way I wholly condemn)
airmon-ng stop wlan0
ifconfig wlan0 down
macchanger –mac 00:11:22:33:44:55 wlan0
airmon-ng start wlan0
-Now we will put the airodump-ng tool into monitor mode, this will allow us to see all of the wireless networks around us.
Now choose the network you want to hack and take note of the BSSID, and the Channel it is one as well as the ESSID. The PWR has to be fairly high to be able to hack it, this is determined by how close you are to the wireless router. The closer you are, the better.
Once you have chosen the wireless network enter the following into the terminal:
This will write capture packets and put them into the “filename” file, we are trying to capture the handshake between the router and wireless connection which will give us the key we need to crack.
airodump-ng mon0 –channel * –bssid **:**:**:**:**:** -w filename
The following step is optional but is highly recommended as it will speed up the process a great deal.
Once “WPA handshake: **:**:**:**:**:**” appears in the top right-hand corner we can move on. If you are having trouble getting the WPA handshake to occur then do step 4.
aireplay-ng -0 1 -a **:**:**:**:**:** -c **:**:**:**:**:** mon0
What this step (4) does is it deauthorizes a wireless connection and trie to re-establish it so it will generate a new handshake to capture. This step ends once you have captured the handshake.
aircrack-ng –w wordlist.lst -b **:**:**:**:**:** filename.cap
Step 5 is now trying to crack the password in “filename.cap” using a list of words, here called “wordlist.lst” you can download a good 200 million word dictionary here (128MB but unzipped is 800MB). However if this wordlist becomes unavailable feel free to drop me a line and I’ll post a new one.
Your computer has to compute the hash value of every password in that list but a computer can go through those 200 million passwords in 6-12 hours.
If the password isn’t found in the dictionary you can try and brute-force the password with this command: (Note this could take a very long time depending on their password strength).
/pentest/password/jtr/john –stdout –incremental:all | aircrack-ng -b **:**:**:**:**:** -w – filename.cap
Note: If you would like some instructions on how to install Backtrack5 have a look at The Geek Net, they have produced a very simple yet very effective tutorial.