New hack cracks 'secure' Bluetooth devices

New Scientist.com ^ | 03 June 2005

[strategofr]

Cryptographers have discovered a way to hack Bluetooth-enabled devices even when security features are switched on. The discovery may make it even easier for hackers to eavesdrop on conversations and charge their own calls to someone else’s cellphone.

Bluetooth is a protocol that allows different devices including phones, laptops, headsets and printers to communicate wirelessly over short ranges - typically between 10 and 100 metres.

Over the past few years security experts have devised many ways of hacking into Bluetooth communications, but most require the Bluetooth security features to be switched off.

In April 2004, UK-based Ollie Whitehouse, at that time working for security firm @Stake, showed that even Bluetooth devices in secure mode could be attacked. His method allowed someone to hijack the phone, giving them the power to make calls as if it were in their own hands. Pairing up

But this technique did not pose a serious risk because it could be performed only if the hacker happened to catch two Bluetooth devices just before their first communication, during a process known as “pairing”.

Before two Bluetooth devices can communicate they must establish a secret key via this pairing process. But as long as the two devices paired up in a private place there was no risk of attack, explains Chris McNab of the UK security firm TrustMatta.

Now Avishai Wool and Yaniv Shaked of Tel Aviv University in Israel have worked out how to force devices to pair whenever they want. “Our attack makes it possible to crack every communication between two Bluetooth devices, and not only if it is the first communication between those devices,” says Shaked.

“Pairing allows you to seize control,” says Bruce Schneier, a security expert based in Mountain View, California. “You can sit on the train and make phone calls on someone else’s phone.” Sniffing the airwaves

During pairing, two Bluetooth devices establish the 128-bit secret “link key” that they then store and use to encrypt all further communication. The first step requires the legitimate users to type the same secret, four-digit PIN into both devices. The two devices then use this PIN in a complex process to arrive at the common link key.

Whitehouse showed in 2004 that a hacker could arrive at this link key without knowing the PIN using a piece of equipment called a Bluetooth sniffer. This can record the exchanged messages being used to derive the link key and feed the recordings to software that knows the Bluetooth algorithms and can cycle through all 10,000 possibilities of the PIN. Once a hacker knows the link keys, Whitehouse reasoned they could hijack the device.

But pairing only occurs the first time two devices communicate. Wool and Shaked have managed to force pairing by pretending to be one of the two devices and sending a message to the other claiming to have forgotten the link key. This prompts the other device to discard the link key and the two then begin a new pairing session, which the hacker can then use. Surprisingly easy

In order to send a “forget” message, the hacker must simply spoof one of the devices personal IDs, which can be done because all Bluetooth devices broadcast this automatically to any Bluetooth device within range.

“Having it done so easily is surprising,” says Schneier. He is also impressed by the fact that Wool and Shaked have actually implemented Whitehouse’s idea in real devices.

They show that once an attacker has forced two devices to pair, they can work out the link key in just 0.06 seconds on a Pentium IV-enabled computer, and 0.3 seconds on a Pentium-III. “This is not just a theoretical break, it’s practical,” says Schneier.

Shaked and Wool will present their findings at the MobiSys conference next Monday in Seattle, Washington, US.

[strategofr]

Those bad guys are clever!

[N3WBI3]

You thin that is bad look at the blue tooth sniper rifle

[supercat]

Security is hard. I've designed a number of devices that uses encryption, but I have no particular illusion of them being terribly strong. On the other hand, I doubt that they're guarding anything of sufficient value to be worth cracking them (especially since other physical attacks on the systems in question would be easier).

Still, it's interesting that even security professionals still can't get everything right.

[flashbunny]

there's something to be said about being slightly behind the technology curve!

[Constantine XIII]

bump

[ArtyFO]

Those Jooooz are clever.

[USF]

Whitehouse showed in 2004 that a hacker could arrive at this link key without knowing the PIN using a piece of equipment called a Bluetooth sniffer.

With the right knowledge, one could read the appropriate "seem" in the cell and see (and change) any PINS and security settings in it anyway.

Still this in interesting and could lead to a whole new wave of destructive viruses sent via bluetooth. *Sigh*

[p23185]

Still, it's interesting that even security professionals still can't get everything right.

All encryption can be broke - it is just the stronger and more robust the encryption, the more resources and time it takes to break. Then you get into export/import regulations. If you want a really strong encryption and you might find your product controlled under the DOS ITAR regulations and that cuts your market potential and drives up price. Design the product so that it will fit under the DOC encryption regulations and it has to be a less robust scheme due to the stated purpose immediately above (holding back military secrets vs. promoting commerce). In today's tech world I wouldn't trust any encryption for more than a few minutes - 128 bit over the Internet and just enough time to make a purchase and get out. I don't trust wireless router encryption because you can buy encryption breakers on the Internet. The longer the connection, the more chance someone can break it.

[zeugma]

O.K., couple this hack to the "bluetooth sniper rifle", and you have a pretty devestating attack. I kinda doubt that is possible without a fairly powerful transmitter on your bluetooth device. Perhaps the "rifle" can also double as a tight beam antenna.

Scary. I'll never own one of these bluetooth devices.

Bet this "rifle" will be pretty effective in sniffing out the new passports the bright folk in FedGov are going to start issuing next year.

[supercat]

If you want a really strong encryption and you might find your product controlled under the DOS ITAR regulations and that cuts your market potential and drives up price.

Out of curiosity, what are the exact rules on that sort of thing? I don't design my encryption systems purposefully to be weak, but rather to be quickly implementable on a cheap micro. The data are passed through a mixture of exclusive-ors, linear shuffling, and non-linear transformation, which are the ingredients of a strong crypto system, but I suspect my transformations probably have some exploitable weakness (they were generated by using a QBASIC random number generator and then arbitrarily flipping a few numbers around by hand).

[FEARED MUTATION]

They refer to a $5000 'bluetooth sniffer' required for these attacks. I'm not really sure why that would be required. It seems to me that any promiscous bluetooth card would do the trick. With a promiscous wifi card and the right software anyone can do lots of tricks in that arena.

[strategofr]

"Still, it's interesting that even security professionals still can't get everything right."

I find it real interesting. by the way, Kevin Mitnick (of "Free Kevin" fame, famous hacker who recently graduated from a 3-yr. term in the federal penitentiary) recently wrote a book, I believe the title is "social engineering" about the human side of breaking into security systems.

I read one interesting vignette, where a guy walks into the lobby of a corporation and starts talking to a secretary there about how he is waiting to meet so-and-so for marketing (he tells her he is a member of the same corporation but from another city).

Just passing the time, and kind of flirting with this woman, it turns out she would like to have a career in marketing, and he can probably help her get started on this within the company. After a while, (when the person he was supposed to meet turns out to be late) this guy convinces this woman to have him assigned to one of the small conference rooms in the building, so he can get some work done. There, he plugs his laptop into an ethernet connection on the wall---inside the company firewall.

[strategofr]

" I don't trust wireless router encryption"

Sure. I don't know the technical side of this, but I figure, at least with landline connections, somebody has to tap into a network somewhere or break into your home or office, etc. In a network, there is some kind of generalized protection. Breaking into a home or office is a lot of work.

Picking up wireless signals on the other hand, is easy. There are probably people out there just grabbing any wireless signal that comes along to see what they can to get out of it.

That's how I look at things.

[zeugma]

Supercat, you might want to check out Why Cryptography is Harder Than It Looks by Bruce Schneier. If you are going to be writing any kind of crypto stuff, I'd strongly recommend that you pick up a copy of "Applied Cryptography" by the same fellow. Given your description, I can pretty much guarantee that whatever you've come up with is incredibly weak. It's hard enough implementing good, strong crypto that has been peer reviewed, much less "rolling your own".