Sunday, July 10, 2011

How to Crack a Wi-Fi Network.

You already know that if you want to lock down your Wi-Fi network, you should opt for WPA encryption because WEP is easy to crack. But did you know how easy? Take a look. 

This tutorial is for information purposes only, and I do not endorse any of the activities discussed within this guide. I nor anyone hosting this guide can be held responsible for anything you do after reading this. What you do with your day lies on your shoulders.

1.Black Track

Today we’re going to run down, step-by-step, how to crack a Wi-Fi network with WEP security turned on. But first, a word: 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.

Dozens of tutorials on how to crack WEP are already all over the internet using this method. Seriously—Google it. This ain’t what you’d call “news.” But what is surprising is that someone like me, with minimal networking experience, can get this done with free software and a cheap Wi-Fi adapter. Here’s how it goes.

What You’ll Need.

Unless you’re a computer security and networking ninja, chances are you don’t have all the tools on hand to get this job done. Here’s what you’ll need:

* A compatible wireless adapter—This is the biggest requirement. You’ll need a wireless adapter that’s capable of packet injection, and chances are the one in your computer is not. After consulting with my friendly neighborhood security expert, I purchased an Alfa AWUS050NH USB adapter, pictured here, and it set me back about $50 on Amazon. Update: Don’t do what I did. Get the Alfa AWUS036H, not the US050NH, instead. The guy in this video below is using a $12 model he bought on Ebay (and is even selling his router of choice). There are plenty of resources on getting aircrack-compatible adapters out there.

* A BackTrack 3 Live CD. We already took you on a full screenshot tour of how to install and use BackTrack 3, the Linux Live CD that lets you do all sorts of security testing and tasks. Download yourself a copy of the CD and burn it, or load it up in VMware to get started. (I tried the BackTrack 4 pre-release, and it didn’t work as well as BT3. Do yourself a favor and stick with BackTrack 3 for now.)

* A nearby WEP-enabled Wi-Fi network. The signal should be strong and ideally people are using it, connecting and disconnecting their devices from it. The more use it gets while you collect the data you need to run your crack, the better your chances of success.

* Patience with the command line. This is an ten-step process that requires typing in long, arcane commands and waiting around for your Wi-Fi card to collect data in order to crack the password. Like the doctor said to the short person, be a little patient.

Crack That WEP

To crack WEP, you’ll need to launch Konsole, BackTrack’s built-in command line. It’s right there on the taskbar in the lower left corner, second button to the right. Now, the commands.

First run the following to get a list of your network interfaces:

airmon-ng

The only one I’ve got there is labeled ra0. Yours may be different; take note of the label and write it down. From here on in, substitute it in everywhere a command includes (interface).

Now, run the following four commands. See the output that I got for them in the screenshot below.

airmon-ng stop (interface)
ifconfig (interface) down
macchanger –mac 00:11:22:33:44:55 (interface)
airmon-ng start (interface)

If you don’t get the same results from these commands as pictured here, most likely your network adapter won’t work with this particular crack. If you do, you’ve successfully “faked” a new MAC address on your network interface, 00:11:22:33:44:55.

Now it’s time to pick your network. Run:

airodump-ng (interface)

To see a list of wireless networks around you. When you see the one you want, hit Ctrl+C to stop the list. Highlight the row pertaining to the network of interest, and take note of two things: its BSSID and its channel (in the column labeled CH), . Obviously the network you want to crack should have WEP encryption (in the ENC) column, not WPA or anything else.

Like I said, hit Ctrl+C to stop this listing. (I had to do this once or twice to find the network I was looking for.) Once you’ve got it, highlight the BSSID and copy it to your clipboard for reuse in the upcoming commands.

Now we’re going to watch what’s going on with that network you chose and capture that information to a file. Run:

airodump-ng -c (channel) -w (file name) –bssid (bssid) (interface)

Where (channel) is your network’s channel, and (bssid) is the BSSID you just copied to clipboard. You can use the Shift+Insert key combination to paste it into the command. Enter anything descriptive for (file name). I chose “yoyo,” which is the network’s name I’m cracking.

You’ll get output like what’s in the window in the background pictured below. Leave that one be. Open a new Konsole window in the foreground, and enter this command:

aireplay-ng -1 0 -a (bssid) -h 00:11:22:33:44:55 -e (essid) (interface)

Here the ESSID is the access point’s SSID name, which in my case is yoyo. What you want to get after this command is the reassuring “Association successful” message with that smiley face.

You’re almost there. Now it’s time for:

aireplay-ng -3 -b (bssid) -h 00:11:22:33:44:55 (interface)

Here we’re creating router traffic to capture more throughput faster to speed up our crack. After a few minutes, that front window will start going crazy with read/write packets. (Also, I was unable to surf the web with the yoyo network on a separate computer while this was going on.) Here’s the part where you might have to grab yourself a cup of coffee or take a walk. Basically you want to wait until enough data has been collected to run your crack. Watch the number in the “#Data” column—you want it to go above 10,000. (Pictured below it’s only at 854.)

Depending on the power of your network (mine is inexplicably low at -32 in that screenshot, even though the yoyo AP was in the same room as my adapter), this process could take some time. Wait until that #Data goes over 10k, though—because the crack won’t work if it doesn’t. In fact, you may need more than 10k, though that seems to be a working threshold for many.

Once you’ve collected enough data, it’s the moment of truth. Launch a third Konsole window and run the following to crack that data you’ve collected:

aircrack-ng -b (bssid) (file name-01.cap)

Here the filename should be whatever you entered above for (file name). You can browse to your Home directory to see it; it’s the one with .cap as the extension.

If you didn’t get enough data, aircrack will fail and tell you to try again with more. If it

Problems Along the Way

With this article I set out to prove that cracking WEP is a relatively “easy” process for someone determined and willing to get the hardware and software going. I still think that’s true, but unlike the guy in the video below, I had several difficulties along the way. In fact, you’ll notice that the last screenshot up there doesn’t look like the others—it’s because it’s not mine. Even though the AP which I was cracking was my own and in the same room as my Alfa, the power reading on the signal was always around -30, and so the data collection was very slow, and BackTrack would consistently crash before it was complete. After about half a dozen attempts (and trying BackTrack on both my Mac and PC, as a live CD and a virtual machine), I still haven’t captured enough data for aircrack to decrypt the key.

So while this process is easy in theory, your mileage may vary depending on your hardware, proximity to the AP point, and the way the planets are aligned. Oh yeah, and if you’re on deadline—Murphy’s Law almost guarantees it won’t work if you’re on deadline.

Video.

2.Comm View For WiFi

CommView for WiFi is a powerful wireless network monitor and analyzer for 802.11 a/b/g/n networks. Loaded with many user-friendly features, CommView for WiFi combines performance and flexibility with an ease of use unmatched in the industry.

CommView for WiFi captures every packet on the air to display important information such as the list of access points and stations, per-node and per-channel statistics, signal strength, a list of packets and network connections, protocol distribution charts, etc. By providing this information, CommView for WiFi can help you view and examine packets, pinpoint network problems, and troubleshoot software and hardware.

CommView for WiFi includes a VoIP module for in-depth analysis, recording, and playback of SIP and H.323 voice communications.

Packets can be decrypted utilizing user-defined WEP or WPA-PSK keys and are decoded down to the lowest layer. With over 70 supported protocols, this network analyzer allows you to see every detail of a captured packet using a convenient tree-like structure to display protocol layers and packet headers. Additionally, the product provides an open interface for plugging in custom decoding modules. WEP and WPA key retrieval add-ons are available subject to terms and conditions.

A number of case studies describe real-world applications of CommView for WiFi in business, government, and education sectors.

CommView for WiFi is a comprehensive and affordable tool for wireless LAN administrators, security professionals, network programmers, or anyone who wants to have a full picture of the WLAN traffic. This application runs under Windows XP/2003/Vista/2008/7 and requires a compatible wireless network adapter. To view the list of the adapters that have been tested and are compatible with CommView for WiFi, click on the link below:

SUPPORTED ADAPTERS

If your wireless card is not on the list, please click here for the technical information, or take advantage of our special offer and get a compatible adapter free of charge!

What you can do with CommView for WiFi

  • Scan the air for WiFi stations and access points.
  • Capture 802.11a, 802.11b, 802.11g, and 802.11n WLAN traffic.
  • Specify WEP or WPA keys to decrypt encrypted packets.
  • View detailed per-node and per-channel statistics.
  • View detailed IP connections statistics: IP addresses, ports, sessions, etc.
  • Reconstruct TCP sessions.
  • Configure alarms that can notify you about important events, such as suspicious packets, high bandwidth utilization, unknown addresses, rogue access points, etc.
  • View protocol “pie” charts.
  • Monitor bandwidth utilization.
  • Browse captured and decoded packets in real time.
  • Search for strings or hex data in captured packet contents.
  • Log individual or all packets to files.
  • Load and view capture files offline.
  • Import and export packets in Sniffer®, EtherPeek™, AiroPeek™, Observer®, NetMon, Tcpdump, hex, and text formats.
  • Export any IP address to SmartWhois for quick, easy IP lookup.
  • Capture data from multiple channels simultaneously using several USB adapters.
  • Capture A-MPDU and A-MSDU packets.
  • And much more!

Who needs CommView for WiFi

  • WLAN administrators.
  • Security professionals.
  • Home users who are interested in monitoring their WLAN traffic.
  • Programmers developing software for wireless networks.

An evaluation version is available in the Download Area.

To purchase this product, add it to the shopping cart (see the link at the top right corner of this page) or visit the Product Catalog. If you purchased this product in the past and would like to purchase an upgrade to the latest version, please visit theUpgrades page.

3. AirCrack NG

Aircrack-ng is an 802.11 WEP and WPA-PSK keys cracking program that can recover keys once enough data packets have been captured. It implements the standard FMS attack along with some optimizations like KoreK attacks, as well as the all-new PTW attack, thus making the attack much faster compared to other WEP cracking tools.In fact, Aircrack-ng is a set of tools for auditing wireless networks.

Packet injection on a phone Aircrack-ng suite now fully works with the internal card of the Nokia N900, including packet injection.

Sources

  • Aircrack-ng 1.1
    SHA1: 16eed1a8cf06eb8274ae382150b56589b23adf77
    MD5: f7a24ed8fad122c4187d06bfd6f998b4

Binaries

  • Aircrack-ng 1.1 (Windows)
    SHA1: 043ac7346cfd4878eb3af9783554873fbb5c28d4
    MD5: 407e342f01f6d46886a9f908b241d53a

     

    Important information:
    This version requires you to develop your own DLLs to link aircrack-ng to your wireless card (it will not work without).
    The required DLLs are not provided in the download and there will be no support for them.
  • Linux packages can be found here.

Previous versions

  • Previous versions of Aircrack-ng can be found here.
  • A backup of the original versions (from Christophe Devine) are available here.
  • Previous versions of Slitaz Aircrack-ng can be found here.
  • Previous versions of our VMWare appliance can be found here.

Other downloads

Sample files

  • test.ivs – This is a 128 bit WEP key file. The key is AE:5B:7F:3A:03:D0:AF:9B:F6:8D:A5:E2:C7.
  • ptw.cap – This is a 64 bit WEP key file suitable for the PTW method. The key is 1F:1F:1F:1F:1F.

Changelog

 

 

 


References: Arrow Webzine &  Nyjil George

 

 

 

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