Your Wi-Fi network is your conveniently wireless gateway to the
internet, and since you're not keen on sharing your connection with any
old hooligan who happens to be walking past your home, you secure your
network with a password, right? Knowing, as you might, how easy it is to crack a WEP password, you probably secure your network using the more bulletproof WPA security protocol.
Here's the bad news: A new, free, open-source tool called Reaver
exploits a security hole in wireless routers and can crack most
routers' current passwords with relative ease. Here's how to crack a WPA
or WPA2 password, step by step, with Reaver—and how to protect your
network against Reaver attacks.
In the
first section of this post, I'll walk through the steps required to
crack a WPA password using Reaver. You can follow along with either the
video or the text below. After that, I'll explain how Reaver works, and
what you can do to protect your network against Reaver attacks
First, a quick note: As we remind often remind readers when we discuss topics that appear
potentially malicious: Knowledge is power, but power doesn't mean you
should be a jerk, or do anything illegal. Knowing how to pick a lock
doesn't make you a thief. Consider this post educational, or a
proof-of-concept intellectual exercise. The more you know, the better
you can protect yourself.
What You'll Need
You don't
have to be a networking wizard to use Reaver, the command-line tool that
does the heavy lifting, and if you've got a blank DVD, a computer with
compatible Wi-Fi, and a few hours on your hands, you've got basically
all you'll need. There are a number of ways you could set up Reaver, but
here are the specific requirements for this guide:
- The BackTrack 5 Live DVD. BackTrack is a bootable Linux distribution that's filled to the brim with network testing tools, and while it's not strictly required to use Reaver, it's the easiest approach for most users. Download the Live DVD from BackTrack's download page and burn it to a DVD. You can alternately download a virtual machine image if you're using VMware, but if you don't know what VMware is, just stick with the Live DVD. As of this writing, that means you should select BackTrack 5 R3 from the Release drop-down, select Gnome, 32- or 64-bit depending on your CPU (if you don't know which you have, 32 is a safe bet), ISO for image, and then download the ISO.
- A computer with Wi-Fi and a DVD drive. BackTrack will work with the wireless card on most laptops, so chances are your laptop will work fine. However, BackTrack doesn't have a full compatibility list, so no guarantees. You'll also need a DVD drive, since that's how you'll boot into BackTrack. I used a six-year-old MacBook Pro.
- A nearby WPA-secured Wi-Fi network. Technically, it will need to be a network using WPA security with the WPS feature enabled. I'll explain in more detail in the "How Reaver Works" section how WPS creates the security hole that makes WPA cracking possible.
- A little patience. This is a 4-step process, and while it's not terribly difficult to crack a WPA password with Reaver, it's a brute-force attack, which means your computer will be testing a number of different combinations of cracks on your router before it finds the right one. When I tested it, Reaver took roughly 2.5 hours to successfully crack my password. The Reaver home page suggests it can take anywhere from 4-10 hours. Your mileage may vary.
Let's Get Crackin'
At this point you should have BackTrack burned to a DVD, and you should have your laptop handy.
Step 1: Boot into BackTrack
To boot
into BackTrack, just put the DVD in your drive and boot your machine
from the disc. (Google around if you don't know anything about live
CDs/DVDs and need help with this part.) During the boot process,
BackTrack will prompt you to to choose the boot mode. Select "BackTrack
Text - Default Boot Text Mode" and press Enter.
Eventually BackTrack will boot to a command line prompt. When you've reached the prompt, type
startx and press Enter. BackTrack will boot into its graphical interface.
Step 2: Install Reaver
Update: This step is no longer necessary, as Reaver comes pre-installed on Backtrack 5 R3. Skip down to Step 3.
Reaver has
been added to the bleeding edge version of BackTrack, but it's not yet
incorporated with the live DVD, so as of this writing, you need to
install Reaver before proceeding. (Eventually, Reaver will simply be
incorporated with BackTrack by default.) To install Reaver, you'll first
need to connect to a Wi-Fi network that you have the password to.
- Click Applications > Internet > Wicd Network Manager
- Select your network and click Connect, enter your password if necessary, click OK, and then click Connect a second time.
Now that
you're online, let's install Reaver. Click the Terminal button in the
menu bar (or click Applications > Accessories > Terminal). At the
prompt, type:
apt-get update
And then, after the update completes:
apt-get install reaver
If all went
well, Reaver should now be installed. It may seem a little lame that
you need to connect to a network to do this, but it will remain
installed until you reboot your computer. At this point, go ahead and
disconnect from the network by opening Wicd Network Manager again and
clicking Disconnect. (You may not strictly need to do this. I did just
because it felt like I was somehow cheating if I were already connected
to a network.)
Step 3: Gather Your Device Information, Prep Your Crackin'
In order to
use Reaver, you need to get your wireless card's interface name, the
BSSID of the router you're attempting to crack (the BSSID is a unique
series of letters and numbers that identifies a router), and you need to
make sure your wireless card is in monitor mode. So let's do all that.
Find your wireless card: Inside Terminal, type:
iwconfig
Press Enter. You should see a wireless device in the subsequent list. Most likely, it'll be named
wlan0, but if you have more than one wireless card, or a more unusual networking setup, it may be named something different.
Put your wireless card into monitor mode: Assuming your wireless card's interface name is
wlan0, execute the following command to put your wireless card into monitor mode:airmon-ng start wlan0
This command will output the name of monitor mode interface, which you'll also want to make note of. Most likely, it'll be
mon0, like in the screenshot below. Make
note of that.
Find the BSSID of the router you want to crack:
Lastly, you need to get the unique identifier of the router you're
attempting to crack so that you can point Reaver in the right direction.
To do this, execute the following command:
airodump-ng wlan0
(Note: If
airodump-ng wlan0 doesn't work for you, you may want to try the monitor interface instead—e.g., airodump-ng mon0.)
You'll see a list of the wireless networks in range—it'll look something like the screenshot below:
When you
see the network you want, press Ctrl+C to stop the list from refreshing,
then copy that network's BSSID (it's the series of letters, numbers,
and colons on the far left). The network should have WPA or WPA2 listed
under the ENC column. Now in BSSID and monitor interface name in hand, you've got everything you need to start up Reaver.
Step 4: Crack a Network's WPA Password with Reaver
Now execute the following command in the Terminal, replacing
bssid and moninterface with the BSSID and monitor interface and you copied down above:reaver -i moninterface -b bssid -vv
For example, if your monitor interface was
mon0 like mine, and your BSSID was 8D:AE:9D:65:1F:B2 (a BSSID I just made up), your command would look like:reaver -i mon0 -b 8D:AE:9D:65:1F:B2 -vv
Press
Enter, sit back, and let Reaver work its disturbing magic. Reaver will
now try a series of PINs on the router in a brute force attack, one
after another. This will take a while. In my successful test, Reaver
took 2 hours and 30 minutes to crack the network and deliver me with the
correct password. As mentioned above, the Reaver documentation says it
can take between 4 and 10 hours, so it could take more or less time than
I experienced, depending. When Reaver's
cracking has completed, it'll
look like this:
A few important factors to consider:
Reaver worked exactly as advertised in my test, but it won't
necessarily work on all routers (see more below). Also, the router
you're cracking needs to have a relatively strong signal, so if you're
hardly in range of a router, you'll likely experience problems, and
Reaver may not work. Throughout the process, Reaver would sometimes
experience a timeout, sometimes get locked in a loop trying the same PIN
repeatedly, and so on. I just let it keep on running, and kept it close
to the router, and eventually it worked its way through.
Also of
note, you can also pause your progress at any time by pressing Ctrl+C
while Reaver is running. This will quit the process, but Reaver will
save any progress so that next time you run the command, you can pick up
where you left off-as long as you don't shut down your computer (which,
if you're running off a live DVD, will reset everything).
Have any experience of your own using Reaver? Other comments or concerns? Let's hear it in the comments.
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