- WEP Cracking: Now that you have gathered information about all the networks around you, and found your target, you will learn how to crack the key that the target uses. In this section you will learn four methods to crack WEP encryption.
- Oct 19, 2010 aircrack-ng – for recovering the WEP key; Start Aircrack-ng GUI and select the log file from above. Also select the encryption(WEP) and Key size (64). Press launch and the WEP key will be revealed.
Video demonstration that shows how to crack a WEP encrypted network with no clients. This is conducted by utilizing aireplay-ng’s fragmentation attack, forging packets with packetforge-ng,. In this article will learn how you can crack WPA2 encryption password file. How to secure Wi-Fi? If you want to secure 100% wireless network, then the best method is to disable wireless, but if you use it, then you cannot. Wi-Fi was first developed in the late 1990s, with WEP encryption which stands. Note: This post demonstrates how to crack WEP passwords, an older and less often used network security protocol. If the network you want to crack is using the more popular WPA encryption, see our.
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.
Secure Your Home Wi-Fi Network
Tech site Ars Technica runs down the basics of securing your home wireless network with the most…
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Note: This post demonstrates how to crack WEP passwords, an older and less often used network security protocol. If the network you want to crack is using the more popular WPA encryption, see our guide to cracking a Wi-Fi network's WPA password with Reaver instead.
How to Crack a Wi-Fi Network's WPA Password with Reaver
Your Wi-Fi network is your conveniently wireless gateway to the internet, and since you're not …
Read more ReadToday 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.
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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 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.
- 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.
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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.
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First run the following to get a list of your network interfaces:
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).Advertisement
Now, run the following four commands. See the output that I got for them in the screenshot below.
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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.
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Now it's time to pick your network. Run:
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), as pictured below. Obviously the network you want to crack should have WEP encryption (in the ENC) column, not WPA or anything else.
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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.
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Now we're going to watch what's going on with that network you chose and capture that information to a file. Run:
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.
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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:
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.Advertisement
You're almost there. Now it's time for:
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.)Aircrack
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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.Advertisement
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:
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.
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If you didn't get enough data, aircrack will fail and tell you to try again with more. If it succeeds, it will look like this:
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The WEP key appears next to 'KEY FOUND.' Drop the colons and enter it to log onto the network.
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.
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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.
Got any experience with the WEP cracking courtesy of BackTrack? What do you have to say about it? Give it up in the comments.
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Wired Equivalent Privacy (WEP) is a security algorithm for IEEE 802.11 wireless networks. Introduced as part of the original 802.11 standard ratified in 1997, its intention was to provide data confidentiality comparable to that of a traditional wired network.[1] WEP, recognizable by its key of 10 or 26 hexadecimal digits (40 or 104 bits), was at one time widely in use and was often the first security choice presented to users by router configuration tools.[2][3]
In 2003 the Wi-Fi Alliance announced that WEP had been superseded by Wi-Fi Protected Access (WPA). In 2004, with the ratification of the full 802.11i standard (i.e. WPA2), the IEEE declared that both WEP-40 and WEP-104 have been deprecated.[4]
WEP was the only encryption protocol available to 802.11a and 802.11b devices built before the WPA standard, which was available for 802.11g devices. However, some 802.11b devices were later provided with firmware or software updates to enable WPA, and newer devices had it built in.[5]
- 5Remedies
- 5.2Implemented non-standard fixes
History[edit]
WEP was ratified as a Wi-Fi security standard in 1999. The first versions of WEP were not particularly strong, even for the time they were released, because U.S. restrictions on the export of various cryptographic technology led to manufacturers restricting their devices to only 64-bit encryption. When the restrictions were lifted, it was increased to 128-bit. Despite the introduction of 256-bit WEP, 128-bit remains one of the most common implementations.[6]
Encryption details[edit]
WEP was included as the privacy component of the original IEEE 802.11 standard ratified in 1997.[7][8] WEP uses the stream cipherRC4 for confidentiality,[9] and the CRC-32 checksum for integrity.[10] It was deprecated in 2004 and is documented in the current standard.[11]
Basic WEP encryption: RC4 keystream XORed with plaintext
Standard 64-bit WEP uses a 40 bit key (also known as WEP-40), which is concatenated with a 24-bit initialization vector (IV) to form the RC4 key. At the time that the original WEP standard was drafted, the U.S. Government's export restrictions on cryptographic technology limited the key size. Once the restrictions were lifted, manufacturers of access points implemented an extended 128-bit WEP protocol using a 104-bit key size (WEP-104).
A 64-bit WEP key is usually entered as a string of 10 hexadecimal (base 16) characters (0–9 and A–F). Each character represents 4 bits, 10 digits of 4 bits each gives 40 bits; adding the 24-bit IV produces the complete 64-bit WEP key (4 bits × 10 + 24 bits IV = 64 bits of WEP key). Most devices also allow the user to enter the key as 5 ASCII characters (0–9, a–z, A–Z), each of which is turned into 8 bits using the character's byte value in ASCII (8 bits × 5 + 24 bits IV = 64 bits of WEP key); however, this restricts each byte to be a printable ASCII character, which is only a small fraction of possible byte values, greatly reducing the space of possible keys.
A 128-bit WEP key is usually entered as a string of 26 hexadecimal characters. 26 digits of 4 bits each gives 104 bits; adding the 24-bit IV produces the complete 128-bit WEP key (4 bits × 26 + 24 bits IV = 128 bits of WEP key). Most devices also allow the user to enter it as 13 ASCII characters (8 bits × 13 + 24 bits IV = 128 bits of WEP key).
A 152-bit and a 256-bit WEP systems are available from some vendors. As with the other WEP variants, 24 bits of that is for the IV, leaving 128 or 232 bits for actual protection. These 128 or 232 bits are typically entered as 32 or 58 hexadecimal characters (4 bits × 32 + 24 bits IV = 152 bits of WEP key, 4 bits × 58 + 24 bits IV = 256 bits of WEP key). Most devices also allow the user to enter it as 16 or 29 ASCII characters (8 bits × 16 + 24 bits IV = 152 bits of WEP key, 8 bits × 29 + 24 bits IV = 256 bits of WEP key).
Authentication[edit]
Two methods of authentication can be used with WEP: Open System authentication and Shared Key authentication.
In Open System authentication, the WLAN client does not provide its credentials to the Access Point during authentication. Any client can authenticate with the Access Point and then attempt to associate. In effect, no authentication occurs. Subsequently, WEP keys can be used for encrypting data frames. At this point, the client must have the correct keys.
In Shared Key authentication, the WEP key is used for authentication in a four-step challenge-response handshake:
- The client sends an authentication request to the Access Point.
- The Access Point replies with a clear-text challenge.
- The client encrypts the challenge-text using the configured WEP key and sends it back in another authentication request.
- The Access Point decrypts the response. If this matches the challenge text, the Access Point sends back a positive reply.
After the authentication and association, the pre-shared WEP key is also used for encrypting the data frames using RC4.
At first glance, it might seem as though Shared Key authentication is more secure than Open System authentication, since the latter offers no real authentication. However, it is quite the reverse. It is possible to derive the keystream used for the handshake by capturing the challenge frames in Shared Key authentication.[12] Therefore, data can be more easily intercepted and decrypted with Shared Key authentication than with Open System authentication. If privacy is a primary concern, it is more advisable to use Open System authentication for WEP authentication, rather than Shared Key authentication; however, this also means that any WLAN client can connect to the AP. (Both authentication mechanisms are weak; Shared Key WEP is deprecated in favor of WPA/WPA2.)
Weak security[edit]
Because RC4 is a stream cipher, the same traffic key must never be used twice. The purpose of an IV, which is transmitted as plain text, is to prevent any repetition, but a 24-bit IV is not long enough to ensure this on a busy network. The way the IV was used also opened WEP to a related key attack. For a 24-bit IV, there is a 50% probability the same IV will repeat after 5000 packets.
In August 2001, Scott Fluhrer, Itsik Mantin, and Adi Shamir published a cryptanalysis of WEP that exploits the way the RC4 ciphers and IV are used in WEP, resulting in a passive attack that can recover the RC4 key after eavesdropping on the network. Depending on the amount of network traffic, and thus the number of packets available for inspection, a successful key recovery could take as little as one minute. If an insufficient number of packets are being sent, there are ways for an attacker to send packets on the network and thereby stimulate reply packets which can then be inspected to find the key. The attack was soon implemented, and automated tools have since been released. It is possible to perform the attack with a personal computer, off-the-shelf hardware and freely available software such as aircrack-ng to crack any WEP key in minutes.
Cam-Winget et al.[13] surveyed a variety of shortcomings in WEP. They write 'Experiments in the field show that, with proper equipment, it is practical to eavesdrop on WEP-protected networks from distances of a mile or more from the target.' They also reported two generic weaknesses:
- the use of WEP was optional, resulting in many installations never even activating it, and
- by default, WEP relies on a single shared key among users, which leads to practical problems in handling compromises, which often leads to ignoring compromises.
In 2005, a group from the U.S. Federal Bureau of Investigation gave a demonstration where they cracked a WEP-protected network in 3 minutes using publicly available tools.[14] Andreas Klein presented another analysis of the RC4 stream cipher. Klein showed that there are more correlations between the RC4 keystream and the key than the ones found by Fluhrer, Mantin and Shamir which can additionally be used to break WEP in WEP-like usage modes.
In 2006, Bittau, Handley, and Lackey showed[2] that the 802.11 protocol itself can be used against WEP to enable earlier attacks that were previously thought impractical. After eavesdropping a single packet, an attacker can rapidly bootstrap to be able to transmit arbitrary data. The eavesdropped packet can then be decrypted one byte at a time (by transmitting about 128 packets per byte to decrypt) to discover the local network IP addresses. Finally, if the 802.11 network is connected to the Internet, the attacker can use 802.11 fragmentation to replay eavesdropped packets while crafting a new IP header onto them. The access point can then be used to decrypt these packets and relay them on to a buddy on the Internet, allowing real-time decryption of WEP traffic within a minute of eavesdropping the first packet.
In 2007, Erik Tews, Andrei Pychkine, and Ralf-Philipp Weinmann were able to extend Klein's 2005 attack and optimize it for usage against WEP. With the new attack it is possible to recover a 104-bit WEP key with probability 50% using only 40,000 captured packets. For 60,000 available data packets, the success probability is about 80% and for 85,000 data packets about 95%. Using active techniques like deauth and ARP re-injection, 40,000 packets can be captured in less than one minute under good conditions. The actual computation takes about 3 seconds and 3 MB of main memory on a Pentium-M 1.7 GHz and can additionally be optimized for devices with slower CPUs. The same attack can be used for 40-bit keys with an even higher success probability.
In 2008, Payment Card Industry (PCI) Security Standards Council's latest update of the Data Security Standard (DSS), prohibits use of the WEP as part of any credit-card processing after 30 June 2010, and prohibits any new system from being installed that uses WEP after 31 March 2009. The use of WEP contributed to the TJ Maxx parent company network invasion.[15]
Remedies[edit]
Use of encrypted tunneling protocols (e.g. IPSec, Secure Shell) can provide secure data transmission over an insecure network. However, replacements for WEP have been developed with the goal of restoring security to the wireless network itself.
802.11i (WPA and WPA2)[edit]
The recommended solution to WEP security problems is to switch to WPA2. WPA was an intermediate solution for hardware that could not support WPA2. Both WPA and WPA2 are much more secure than WEP.[16] To add support for WPA or WPA2, some old Wi-Fi access points might need to be replaced or have their firmware upgraded. WPA was designed as an interim software-implementable solution for WEP that could forestall immediate deployment of new hardware.[17] However, TKIP (the basis of WPA) has reached the end of its designed lifetime, has been partially broken, and had been officially deprecated with the release of the 802.11-2012 standard.[18]
Implemented non-standard fixes[edit]
WEP2[edit]
This stopgap enhancement to WEP was present in some of the early 802.11i drafts. It was implementable on some (not all) hardware not able to handle WPA or WPA2, and extended both the IV and the key values to 128 bits.[19] It was hoped to eliminate the duplicate IV deficiency as well as stop brute force key attacks.
After it became clear that the overall WEP algorithm was deficient (and not just the IV and key sizes) and would require even more fixes, both the WEP2 name and original algorithm were dropped. The two extended key lengths remained in what eventually became WPA's TKIP.
WEPplus[edit]
WEPplus, also known as WEP+, is a proprietary enhancement to WEP by Agere Systems (formerly a subsidiary of Lucent Technologies) that enhances WEP security by avoiding 'weak IVs'.[20] It is only completely effective when WEPplus is used at both ends of the wireless connection. As this cannot easily be enforced, it remains a serious limitation. It also does not necessarily prevent replay attacks, and is ineffective against later statistical attacks that do not rely on weak IVs.[21]
Dynamic WEP[edit]
Dynamic WEP refers to the combination of 802.1x technology and the Extensible Authentication Protocol. Dynamic WEP changes WEP keys dynamically. It is a vendor-specific feature provided by several vendors such as 3Com.
The dynamic change idea made it into 802.11i as part of TKIP, but not for the actual WEP algorithm.
See also[edit]
References[edit]
- ^IEEE Standard for Information Technology- Telecommunications and Information Exchange Between Systems-Local and Metropolitan Area Networks-Specific Requirements-Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. IEEE STD 802.11-1997. November 1997. pp. 1–445. doi:10.1109/IEEESTD.1997.85951. ISBN1-55937-935-9.
- ^ abAndrea Bittau; Mark Handley; Joshua Lackey. 'The Final Nail in WEP's Coffin'(PDF). Retrieved 2008-03-16.Cite journal requires
|journal=
(help) - ^'Wireless Adoption Leaps Ahead, Advanced Encryption Gains Ground in the Post-WEP Era' (Press release). RSA Security. 2007-06-14. Archived from the original on 2008-02-02. Retrieved 2007-12-28.
- ^'What is a WEP key?'. Archived from the original on April 17, 2008. Retrieved 2008-03-11. -- See article at the Wayback Machine
- ^'SolutionBase: 802.11g vs. 802.11b'. techrepublic.com.
- ^Fitzpatrick, Jason (September 21, 2016). 'The Difference Between WEP, WPA and WAP2 Wi-Fi Passwords'. How to Geek. Retrieved November 2, 2018.
- ^Harwood, Mike (29 June 2009). 'Securing Wireless Networks'. CompTIA Network+ N10-004 Exam Prep. Pearson IT Certification. p. 287. ISBN978-0-7897-3795-3. Retrieved 9 July 2016.
WEP is an IEEE standard introduced in 1997, designed to secure 802.11 networks.
- ^Walker, Jesse. 'A History of 802.11 Security'(PDF). Rutgers WINLAB. Intel Corporation. Archived from the original(PDF) on 9 July 2016. Retrieved 9 July 2016.
IEEE Std 802.11-1997 (802.11a) defined Wired Equivalent Privacy (WEP).
- ^'WPA Part 2: Weak IV's'. informit.com. Archived from the original on 2013-05-16. Retrieved 2008-03-16.
- ^'An Inductive Chosen Plaintext Attack against WEP/WEP2'. cs.umd.edu. Retrieved 2008-03-16.
- ^IEEE 802.11i-2004: Medium Access Control (MAC) Security Enhancements(PDF). 2004. Archived from the original(PDF) on 2007-11-29. Retrieved 2007-12-18.
- ^Nikita Borisov, Ian Goldberg, David Wagner. 'Intercepting Mobile Communications: The Insecurity of 802.11'(PDF). Retrieved 2006-09-12.Cite journal requires
|journal=
(help)CS1 maint: multiple names: authors list (link) - ^'SECURITY FLAWS IN 802.11 DATA LINK PROTOCOLS'(PDF). berkeley.edu.
- ^'Wireless Features'. www.smallnetbuilder.com.
- ^'T.J. Maxx data theft likely due to wireless 'wardriving''. Retrieved 2012-09-03.
- ^'802.11b Update: Stepping Up Your WLAN Security'. networkmagazineindia.com. Retrieved 2008-03-16.
- ^'WIRELESS NETWORK SECURITY'(PDF). Proxim Wireless. Retrieved 2008-03-16.Cite journal requires
|journal=
(help) - ^'802.11mb Issues List v12'(excel). 20 Jan 2009. p. CID 98.
The use of TKIP is deprecated. The TKIP algorithm is unsuitable for the purposes of this standard
- ^'WEP2, Credibility Zero'. starkrealities.com. Retrieved 2008-03-16.
- ^'Agere Systems is First to Solve Wireless LAN Wired Equivalent Privacy Security Issue; New Software Prevents Creation of Weak WEP Keys'. Business Wire. 2001-11-12. Retrieved 2008-03-16.
- ^See Aircrack-ng
External links[edit]
Retrieved from 'https://en.wikipedia.org/w/index.php?title=Wired_Equivalent_Privacy&oldid=916496227'