Main article: How to Protect Your Wireless Network
I have previously posted 2 articles on:
- How to Crack WEP Wireless with BackTrack 4 running on Windows
- How to Crack WPA & WPA2 Wireless with BackTrack 4 running on Windows
This article explains how to crack a WEP, WPA, or WPA2 using a Graphical User Interface (GUI) instead of writing codes. I would recommend that you check out the previous articles to understand the steps involved in the process.
Before you begin
- You need to have BackTrack installed and running on VMWare Player. How to Install VMWare & Backtrack 4
- Check if your wireless adapter is compatible with Backtrack 4 from List of compatible adapters
- I am using the Alfa AWUS036H which is a very well known usb wireless adapter because of its good performance and cheap price.
- Make sure that your wireless adapter is plugged into your virtual machine. In VMWare goto the menu “Virtual Machine” -> “Removable Devices” -> “YOUR ADAPTER MUST BE TICKED”
Downloading & Installing GRIM WEPA
First, we need to download and install “GRIM WEPA” inside Backtrack 4:
- Download: Goto http://code.google.com/p/grimwepa/ and download “grimstall.sh” & the latest version of “grimwepa”. In my case: it is “grimwepa_1.0.jar”
- Copy the files into the virtual machine by dragging & dropping them into the virtual machine
- Launch Konsole and run the following command
./grimstall.sh install /pentest/wireless/grimwepa/
Running GRIM WEPA
- Select the wireless interface that you want to use to put in monitor mode. In my case: wlan0
- Select the monitoring interface from. In my case: mon0
- Make sure “All Channels” is checked
- Hit “Refresh Targets” until the list of available networks appear.
- Hit “Stop scanning”
- Select the network that you wish to crack
Cracking a WEP Network
If the network that you have selected is WEP encrypted then follow these steps:
- Select “ARP-Replay” as the Attack method
- Tune the Injection rate to “600”
- Click “Start Attack” (if Captured IVs doesn’t increase then restart the attack)
- Cracking will automatically start when number of IVs collected reach 10,000. In case it wasn’t able to crack it at 10,000 then it will keep collecting more IVs and try to crack
- In the end it should show you the WEP key in the status bar as shown below
Cracking a WPA/WPA2 Network
If the network that you have selected is WPA or WPA2 encrypted follow these steps:
- Click “Start Deauth + Handshake Capture Attack”. You need someone who is already using the wireless network that you are attacking, or you have to wait until someone connects to it. So you might need to keep it running for some time
- Wait until you see “Handshake was captured!”
- Now select the dictionary file that you wish to use to crack the password and click “Crack WPA (Dictionary Attack)”
- In case the password wasn’t cracked then you need to try another dictionary file
- In case the password was cracked then you should see it in the status bar as shown below
As mentioned in my previous articles that cracking a WPA or WPA2 network is directly related to the complexity of the password and the dictionary file that you are using. This means that you might be able to crack the password in a matter of seconds or not crack it at all.
GRIM WEPA is a GUI application used to automate the process of cracking a WEP, WPA, or WPA2. Cracking a WEP protected wireless network is almost guaranteed to succeed, easy, and fast to achieve. The success of cracking a WPA or WPA2 wireless network is directly related to the complexity of the password and the dictionary file that you’re using.
This is why you should set your home wireless network to be WPA2 protected with a long password that contains a variety of letters, capital letters, numbers, and symbols. Check How to Protect Your Wireless Network for more details.
Feel free to ask questions or let me know if I have missed something by leaving a comment below.