Cell Phone Encryption Exploit Demonstrated

Saxophonist brings us a story from Forbes about security researchers who demonstrated a new method for breaking the encryption on GSM cellular signals. The presentation was made at the recent Black Hat conference, and it's notable for the fact that the technique only requires "about half an hour with just $1,000 in computer storage and processing equipment." The researchers also claim to have found a faster method, which they intend to market for $200,000 - $500,000. Quoting: "Undetectable, 'passive' systems like the one that Muller and Hulton have created aren't new either, though previous technologies required about a million dollars worth of hardware and used a "brute force" tactic that tried 33 million times as many passwords to decrypt a cell signal. All of that means, Hulton and Muller argue, that their cheaper technique is simply drawing needed attention to a problem that mobile carriers have long ignored--one that well-financed eavesdroppers may have been exploiting for years. 'If governments or other people with millions of dollars can listen to your conversations right now, why shouldn't your next-door neighbor?' Muller says."

Not too afraid

While this is an extremely powerful re-discovery, I'm not that afraid of average Joe attempting to listen to my conversations, which are boring if anything most of the time. It would still probably take a reasonably quick computer and technical know-how to implement this kind of scheme on a usable scale. Plus, if the FBI and CIA already have the privilege to tap into my conversations, then the fear of security loss is already somewhat of a non-unique one.

Re:Not too afraid

Ever talk about hating your job?

Yes often, even when at work. Its also no secret that I hate my top boss.

Lying on taxes is pretty much a national trait around here (Denmark), so again yes - some of us have no worries.

But I do despise the fact that someone can listen in on stuff, even though most of what we do is no secret, its still something that annoys me.

Overkill for neighbours

why shouldn't your next-door neighbor?

Considering how many mobile users seem to scream into the damn things this may almost be redundant! /joke

Re:Overkill for neighbours

But my neighbors are speaking Klingon when they come out of the basement to talk in their mobile. How could this technology help me?

They're also saying "ghob" out loud... also I think my other neighbors are raptors...

Re:Overkill for neighbours

How could this technology help me?

1. Record conversations.
2. Open subspace diplomatic channel to the Romulans [wikipedia.org].
3. Sell the conversations as intelligence data.
4. Profit!

There never was end-to-end encryption...

There are stories like this all the time, but tech people still have trouble convincing most users that end-to-end encryption is important. How is it that it caught on for the web (credit card payments over SSL), but still barely for personal communications (gpg, encrypted IM)? Even in the situations where it's easy to use encryption, many users still can't be made to care -- especially if it's not something enabled by default. Maybe just that those doing the sniffing are suitably quiet about it...
--
Electronics kits for the digital generation. [nerdkits.com]

Re:There never was end-to-end encryption...

Ya know, it *is* strange. Take, for example, Pidgin (formerly GAIM). There's about two dozen plugins for it. One of the plugins is Pidgin-Encrypt [sourceforge.net] which does everything that you would expect (except possibly for some sort of certificate system) and is about as secure as ssh. Does it come with Pidgin by default? No. Is it enabled by default? No. Why not? Why is encryption still considered some opt-in alternative? Considering that it takes both parties to consciously choose to install this plug-in, the grand total of people who use it is about 10.

 

Re:There never was end-to-end encryption...

How is it that it caught on for the web (credit card payments over SSL), but still barely for personal communications (gpg, encrypted IM)?

That's a very good question.

One idea I've heard is that when SSL was first developed, the web was in its infancy and nobody really felt happy about the idea of sending their credit card details over it. The fact that it was relatively easy to eavesdrop on a computer network was fairly well known. This was no good to anyone who wanted to do business (OK, porn sites) over the web, and so SSL solved that problem by providing reassurance that nobody was eavesdropping.

The telephone system, on the other hand - that's been around so long that it's familiar technology and relatively few people are aware of how insecure it is. If you think GSM is bad (it's actually not that poor, and 3G introduces AES encryption), consider your land line. No encryption whatsoever and an analogue signal (so no computer equipment or specialised unusual codecs required to tap) between you and the telephone exchange.

Re:There never was end-to-end encryption...

automation, pure and simple...

the browsers come pre-equiped and will use it when ever a url starts with https rather then http.

also, the encryption isnt used to verify that whoever is sitting in front of the computer is who he or she claims to be, for that you have third party stuff like pads of one time codes, code generators and similar.

for im and mail on the other hand one have the, in the eyes of the non-techie user, laborious process of generating and exchanging keys, and making sure that the keys belong to the person one wants to communicate with.

only way i see this change is if we could turn the mobile phone into a digital key carrier. meet someone, exchange keys pr phone just as one would exchange phone numbers, im/mail address and similar, and so on.

or maybe the social network sites should allow one to upload ones public key just as on enter above numbers and addresses?

basically one have to find a way to bring the exchange of public keys into the fabric of ones social interaction. sadly i dont think that will happen any time soon...

Obligatory

'If governments or other people with millions of dollars can listen to your conversations right now, why shouldn't your next-door neighbor?'

Because the Government hates the competition?

GNUradio is also up to GSM cracking

and i'll bet they won't charge anything.

check out some movie about the GSM state of security [1] and mod me informative. ;)

[1] http://chaosradio.ccc.de/camp2007_m4v_2015.html [chaosradio.ccc.de]

Coming soon, try it yourself...

Unless their patent application is kept confidential by the government for reasons of national security, it will be published within 18 months. You'll be able to learn how the trick works from it (if you're an expert in the field and you cannot make it work, no patent should be granted). You're not allowed to exploit that commercially, of course, but at least you can have fun and pull a few pranks with it. You could claim you're psychic.

I'm wondering how you ever could tune in to the correct conversation, with thousands of mobile phones transmitting at the same time.

Bert

Re:Coming soon, try it yourself...

I'm wondering how you ever could tune in to the correct conversation, with thousands of mobile phones transmitting at the same time.

GSM phones identify themselves to the network using a unique International Mobile Equipment Identity (IMEI) #.

This number is usually printed on the phone somewhere under the battery cover & is retrievable from the phone's software.

Here's your answer.

'If governments or other people with millions of dollars can listen to your conversations right now, why shouldn't your next-door neighbor?'

It's called common decency, something that's clearly fading away in our society.

Privacy the least of our concerns

My first thought about this was privacy and the government. Obviously.

From my understanding though, this encryption is certainly not applied over the whole transmission, meaning endpoint to endpoint. Just the handset to the tower.

The government does not actually need to crack this encryption, or even intercept transmission between handsets and towers. They can just order digital wiretaps, which cannot be detected. Speaking of which, I have always been amused when people state they you can just buy hardware to detect that too. The location of the handset is easily determined, and in most cases the identity of the user. The government already has the ability to access all of this information with the cooperation of the telecommunications companies anyways. With Telco Immunity being pushed, there won't even be room to dispute it anymore.

So not trivializing the serious issues with our privacy and the government, they are still the least of our concern here.

What strikes me as very problematic is that this opens up a whole new "market" for identity theft, banking fraud, etc. I do quite a lot of business over the phone, and just about every single company uses the touch tones to gather data. Capturing the the numbers by listening to the tones is trivial. This can be done quite easily by software and hardware.

So if all the popular company phone numbers are known, and all the data being sent to it by customers can be recorded, this presents quite a security problem. With the right amount of equipment you can start capturing all sorts of data being sent over the phone. It will only be a matter of time before you gain enough information to compromise someones identity.

I am not worried about my neighbors, not worried about my government, but I am very worried about the stranger interested in the fact I called Washington Mutual.

Re:Privacy the least of our concerns

Yeah, you're still not getting it. The US government often likes to listen to cell phone conversations in, say, oh, I don't know, Iraq? Syria? A lot of other places where GSM is the cheapest technology available. Some governments like to do the same thing inside the USA. There aint no getting a wiretap when you're an agent for a foreign government.

Lets look at some facts....

This is a good hack, and impressive work by all involved, but its rather limited in its application. It only works against the GSM A5/1 encryption algorithm. While there is a huge amount of A5/1 equipment out there it's a ~30 year old algorithm that was designed to run on battery powered equipment from the late 80s.

New GSM equipment already supports A5/3 [gsmworld.com] which is still secure. I think the main impact of this hack is going to be some sensational headlines and a big push to make A5/3 universally available.

not stupid after all

knowledge of this can *only* have some impact if you tell everyone about it. just look WEP, better encryption is the way to go.

Re:because

It's really a matter of publicizing the weakness to the point where manufacturers and network providers are forced to do something about it. Average people generally don't care about issues like this until they're really an issue.

Re:because

Regarding government interception, GSM encryption is only from phone to station. At the Telco it's plaintext. So govs can (and probably do) listen to GSM phone calls. Should be common knowledge amongst telco people.

So GSM crypto even if it was uncrackable is not very helpful if you're really trying to hide your comms.

Someone I knew once claimed to have extra crypto on his GSM phone so that he could talk "securely" to other people similarly equipped.

Let him be...

'If governments or other people with millions of dollars can listen to your conversations right now, why shouldn't your next-door neighbor?' Muller says."

What a stupid comment. In other words, if some people are going to break the law, let's make sure everyone can. Good idea.

Let him sit on his couch eating Cheetos. He has the right to be happily oblivious as every personal right slowly disappears because no one is complaining (too busy eating Cheetos!) while the technology that makes it possible keeps getting cheaper and more powerful.

Re:For those three people ...

Newsflash - most of the world outside the US uses GSM.

Re:For those three people ...

Don't you mean 2.3 billion people [prnewswire.com]? I mean, over 80% of the world's cell phones? The world doesn't end at your doorstop, you know?

Re:That would be awesome

message to your significant other: if he ever uses a non-gsm phone get the frying pan :)

Re:That would be awesome

Turns out that if you don't know the person and what they're talking about then the conversations are extremely boring. People just aren't that interesting on the phone.

I had the exact opposite experience. I found other people's conversations fascinating, but within a couple of days I'd heard stuff that was so personal it made me realize I shouldn't be listening. Thinking about it, experiencing that at 14 probably led me to believe in people's right to privacy and anonymity today. It certainly led to me never buy a cordless house phone.