The Fern WIFI cracking application that is shipped with Kali Linux is a very powerful tool for cracking a wireless network. You will need a wireless password list file to use in conjunction with this application to search for passwords. There are many of these on the Internet; search for one that is as large as possible to ensure that it will contain enough passwords to enable you to attack the networks you are after.
- Load fern as root and select the wireless interface that you will be using to crack the network.
- Then click the antenna icon to scan for target wireless networks.
- Once you have found some wireless networks, select the one that you wish to attack with the WIFI icon.
- This will open the attack panel.
- Then click the network you wish to attack.
- Click the browse button to select a password file.
- Once you have added a password file; click the Attack button to begin bruteforcing the WPA2 pasphrase.
This attack could take a very long time to complete depending upon the complexity of the WPA2 passphrase and the amount of passwords in the password file. If you are successful; the WPA2 passphrase will be displayed for you to use. I do not think that my WIFI will be cracked by this program though unless I create another network with a weak PSK. But that will not happen. I am just writing this to illustrate how to attempt this attack. But if you are successful; then more power to you. But you will need a massive password file.
Download a nice one here: https://forums.hak5.org/index.php?/topic/29308-13gb-44gb-compressed-wpa-wpa2-word-list-982963904-words/. 4.4 gigabyte download. Unpacks to 13 Gigabytes.
If you wish to generate your own Rainbow Tables for cracking WPA2 networks; you may use this utility. Pyrit. This will generate a huge list of possible passwords using the power of your GPU. The faster the better.
Download it here: https://code.google.com/p/pyrit/. This is available for Macintosh OSX, BSD and Linux.