WPA Weak Key Cracker Posted

Glenn Fleishman writes "The folks at TinyPEAP released a cracking tool to break Wi-Fi Protected Access (WPA) keys. WPA is the replacement for weak WEP keys in the original 802.11b specification. Robert Moskowitz of ICSA Labs released a paper almost exactly a year ago documenting how WPA keys that were short and lacked randomnness could be subject to cracks. This tool automates the process. Moskowitz advised choosing passphrases of more than 20 characters or generating random keys of at least 96 bits, but preferably 128 bits. Some tools exist to produce better keys, including chipmaker Broadcom's SecureEZSetup (in selected hardware) and Buffalo Technologies' hardware-based AOSS for automatic key generation and propagation. Enterprise-based WPA with 802.1X doesn't have this weakness: each user gets a long WPA key that's randomly generated and uniquely assigned--and can be frequently changed during a session."

Comments

By its nature...

[The Islamic Fundamen]

When you really think about it, by nature wireless networking can never be too secure. I mean, your data is being broadcasted across the air to another point. Think about it.

Re:By its nature...

[Anonymous Coward]

When you really think about it, by nature the internet can never be too secure. I mean, your data is being transmitted through dozens of other servers to another point. Think about it.

Re:By its nature...

[wcdw]

Theoretically, perhaps - but how secure does it need to be? All wireless traffic in my home uses SSH tunnels between the laptop and the firewall.

When it becomes possible to conveniently crack SSH tunnels, I'll start to worry. By then, I'm sure there will be something better available. Meanwhile, you can sniff those ESP packets to your heart's content.

This is trivial under Linux, and not much more difficult under Winblows (clients), and I'm surprised more people don't suggest it as an alternative to WEP/WPA.

(My girlfriend uses Winblows w/ SSH Sentinel, and has only had one problem that rebooting wouldn't fix - in over 3 years. That one? Installing XP / SP2 turns on the [useless] firewall, which blocks the ports needed by the VPN.)

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Re:By its nature...

[slashdot.org]

When you really think about it, by nature wireless networking can never be too secure. I mean, your data is being broadcasted across the air to another point. Think about it.

I guess that's an understandable misconception about security. But security has by nature nothing to do with wireless or wired.

Good security is based on the principle that other people WILL have access to your encrypted data.

Unfortunately, the people that implemented security in the wireless protocols did a piss-poor job and left it vulnerable to (known!) attacks.

However, if you just ran IPSec or something over your wireless connection, you'd be fine.

Re:By its nature...

[Anonymous Coward]

Installing XP / SP2 turns on the [useless] firewall, which blocks the ports needed by the VPN.)

That's what firewalls do...they block ports. Be they SP2 or some other variation this has nothing to do with the design of Microsoft's firewall and everything to do with the concept of firewalls.

But since you've called Windows "Winblows" and labelled te firewall useless it's obvious you're lacking sufficient knowledge to know why the problem occured.

Re:By its nature...

[Anonymous Coward]

Who modded this insightful? Of course proper security always assumes that everything you transmit is captured inbetween.

Real security makes it really hard to use the captured data without the key, which should never be transmitted cleartext.

Re:By its nature...

[KillerCow]

When you really think about it, by nature wireless networking can never be too secure. I mean, your data is being broadcasted across the air to another point. Think about it.

Your wired network can't be too secure either. All that you need to do is attach a listening device to a wire somewhere. Or just compromise a machine.

See the sibling post about how the basis of cryptography is asuming that someone has access to your encrypted data and the encryption algorithm. All security rests in the key. Cryptographic algorithms exist that can make it infeasable to decrypt a block of cyphertext without the key.

Re:By its nature...

[Anonymous Coward]

Wireless is obviously less secure than wired networks... but these are also vulnerable to:
- TEMPEST attacks (measuring the electromagnetic field around the wires to find out what information is going trhough)
- unprotected switches allowing an external laptop to plug into the company network (and to arp-spoof you)

To be secure, you sometimes have to be paranoied... for instance, I take for granted that all the packets on my network can be seen, either by a war-driver or by someone using the wired network.

The only response is: encryption.
You want to secure the trafic between your wireless laptops and your servers? Use IPSEC! Better yet, L2TP/IPSEC (compatible with the MS VPN client).
You want to provide secure services? Force the use of HTTPS (when relevant) and POPS/IMAPS. Use the SASL/TLS capabilities of your MTA (who said postfix?).

And always remember: the level of security for a network shall always be directly linked with the sensitivity of the data going trough.

Re:By its nature...

[Alejo]

still missing: session keys and host keys. :)
Plus how good is your OS at getting entropy? What symmetric encryption algorithm? What key exchange algorithm?
And about ssh over vpn... a friend (known player @ crypto) told me once that you should never assume that re-encrypting would improve security, unless you are using a well known and tested method of mixing both encryption systems.
Intention of this post is not bitching, but to try to make ppl aware it's not just "i use XXX, so im safe", but a very complex subject.

Odds of implementation?

[IamGarageGuy 2]

The odds of Joe sixpack going the extra step of making a 20 character key is not good. WiFi setups are all the rage and now can all be broken into even after you spend an hour telling someone that they have to use WEP.

Re:What Morons

[PedanticSpellingTrol]

Jesus christ, I hope you don't have a job in security. If all your packets are unencrypted, anybody can sniff them, see what MAC addresses are recieving traffic, and thus are on the whitelist. From there, it's a simple matter to spoof the MAC in software. This feature is built into linux, windows and OS X. The myth that MAC addresses are a universally unique identifier is dangerous and has to be dispelled.

Re:What Morons

[chizu]

"ifconfig wlan0 hw ether [mac address]" sets your wlan card's mac address under Linux. There is probably a way to do so under Windows as well.

don't blame WPA

[nbert]

...if your key is asdf - the attack is based on a dictionary. This weakness relies on human nature after all.

Btw: The Tips and Tricks section of this newsletter is a good ressource if you want to create passes which are harder to guess.

Comment removed

[account_deleted]

Comment removed based on user account deletion

Re:Just name all your specific MAC addresses

[hsidhu]

ummmm how hard is it to sniff the traffic, and get the MAC addess that is allowed and then spoof it?

Asside: WEP = Wired Equivalency Protocol

[KillerCow]

As an aside to the above point, the original "WEP" stood for "Wired Equivalency Protocol." They chose that because it acknowledged that wires weren't inherently secure either. It's name didn't claim security at all... just that it was equivalent to a wire. The inside joke was that that didn't mean anything from a security standpoint either.

Re:Just name all your specific MAC addresses

[zakezuke]

How many home networks really need to allow random MAC addresses access?

How many home users know what a MAC address is?

Re:Just name all your specific MAC addresses

[IHateSlashDot]

You're kidding right? MAC filtering provides absolutely no added security. Once the encryption is broken, spoofing a MAC address is trivial.

Re:Suggestion

[igrp]

From reading all the threads and flame wars going on here, it appears that WEP, WPA and even MAC address filtering is easy to crack, if someone was determined enough to do it.

Well, there are different schools of thought when it comes to SoHo/low bandwidth WAN access security.

You are attempting to lock your network down so that a potential attacker cannot use your connection. The other approach lock your network down just enough to make a cracker not want to bother and to move on to the next, easier target (ie. your neighbors' access points).

The former approach generally works just fine if your goal is to deny a potential attacker access to your network bandwidth. It won't really stop a determined attacker who isn't just in it for a free-ride but who wants to steal specific data. If that's part of your threat model, chances are wireless isn't really for you. The downside is that this is pretty inconvenient. And since convenience is the big selling point when it comes to wireless networking, most people just won't take that route.

Those people who have WEP and MAC address filtering enabled, basically want to protect themselves against random, unsophisticated wardriving. It won't help defend against a determined attacker and probably won't even scare off the teenager next door with too much time on his hands. The point isn't really to have good access security. It's just to raise the bar enough to be unatractive enough of a target. Think of it as a "I don't have to outrun the bear, I just have to outrun you" scenario.

What are "short" WPA keys supposed to be?

[rpp3po]

It is easy to see, that the original poster of this story has no clue about encryption. There are several misconceptions in his posting:

1. He writes: "WPA is the replacement for weak WEP keys in the original 802.11b specification". This is wrong. "weak key" ist a crypographic term for - wonder - weak keys, like 128 bit, consisting of 1's only (1111111111111...). For like 30 years, even WEP, has taken measures to prevent this kind of keys during use. WEP's problem in fact is the deterministic generation of IV's of the keystream, not weak keys.
2. "Moskowitz advised choosing passphrases of more than 20 characters or generating random keys of at least 96 bits, but preferably 128 bits." That's also misunderstood. The PSK (pre shared key) even when not using 802.1X is always 256-bit. It's generated -from- a passphrase that you type in. A passphrase like "abc" e.g. contains less than 16 bits of security. So a WPA key generated from the passphrase "abc", although still being 256-bit, can be cracked within the time of a 16 bit brute force attack. This is done by simply generating WPA keys from all passphrases between "aaa" and "zzz". So you always use 256 bit keys (PSK's), but they can be generated from much smaller passphrases.
3. "each user gets a long WPA key". See above. The keys are always the same size of 256 bit. When using 802.1X there is only maximum "randomness". That's the difference. It think the poster still thinks that WPA works like WEP where you actually use different key lengths.

One could think that I'm very picky about his words. I think not. Especially in cryptography it is important to know exactly what part of a cryptographic chain you're talking about, when talking about weaknesses. TinyPEAP seems to be just a tool for people like the original poster and script kiddies, who are in fact NOT knowing what they are talking about. It's just a bruteforce tool to try out WPA passphrases. This is supposingly faster for people using short passphrases than bruteforcing keys directly.

Re:What are "short" WPA keys supposed to be?

[eggboard]

I'm the original poster. You're reading what I wrote with the lack of knowledge necessary to comment on it.

1. All WEP keys are susceptible to nearly the same degree of being broken by collecting enough data passively. Thus, they are all weak. From a definition of weak keys at an online dictionary: "In the extreme, a poor cipher design is simply one with a very large number of weak keys."

2. No, you're misreading this, too. Moskowitz (see his paper) is talking about the seed data, not the resulting way in which it's represented. The lack of randomness in seed data is the problem. So if you take 16 bits of data and turn them into a hex WPA key, it doesn't matter whether it's represented as 256 bits. The whole problem is the algorithm by which it's processed. You need to start with at least 128 bits of data (into hex) that are non-dictionary, non-weak. (In this sense, weak is much more limited.)

3. Sigh. Each user gets a key that has a full 256 bits of randomness.

You are being picky about your words incorrectly.