IBM Crypto Up For Grabs?

An Anonymous Coward writes: "BBC Newsnight have tonight shown an article about a groups of hackers who are about to release details of the vulnerability of the IBM Cryptographical processors. ( Details here.) The BBC article can be watched online here. Alan Cox makes a starring role ;)" windowlicker adds some detail: "Mike Bond and Richard Clayton, from Cambridge University, have cracked IBM's 4758 crytoprocessor running the 'Common Cryptographic Architecture' (CCA). You can do the same with $1000-worth of hardware and the info from here. Many banks use this system for protecting PINs." The video file requires Real software; here's the BBC's article online for those of us without.

Comments

Lessons to be learned:

[alewando]

1. Hardware encryption will always be more difficult than software-based encryption to patch when vulnerabilities arise. There are advantages that can offset this when deciding whether or not to go with hardware, but contingency plans must be put in place for yanking the hardware back when a vulnerability is discovered.
   
2. Homogeneity in network environments is nearly always bad. This particular vulnerability wouldn't be nearly as critical if it weren't for the fact that all banks who use these cryptoprocessors either use the same ones or use ones that are similar enough that vulnerabilities like these can be used on more than one "different" type. It's much harder to crack one and then crack another and another than it is to crack one and have therefore cracked them all.
   

At least I have high hopes that this vulnerability will be patched forthwith -- not only does IBM have a better track record than certain other corporations, banks have both the money and the clout to demand and receive.

Re:Lessons to be learned:

[swillden]

Hardware encryption will always be more difficult than software-based encryption to patch when vulnerabilities arise.

Actually this is incorrect. The 4758 is eminently software-patchable because it's a software device inside a secure hardware module. In fact the most difficult and complex part of the 4758 design is the support for secure upgrades of critical software components in a hostile environment. It uses a combination of carefully designed boot stages coupled with hardware interlocks (they call it a "ratchet") that gradually increase the complexity and decrease the access of the software that can be loaded. Thus they start with a miniature boot PROM whose code can be thoroughly proven (in the mathematical sense) to be correct, but whose only purpose is to be able to load the next stage after validating the signature on it. After that second stage is loaded, the "ratchet" is moved and the region of memory that has been loaded is now unwritable. It's very cool stuff, you can read about it in the design whitepaper.

Homogeneity in network environments is nearly always bad. This particular vulnerability wouldn't be nearly as critical if it weren't for the fact that all banks who use these cryptoprocessors either use the same ones or use ones that are similar enough that vulnerabilities like these can be used on more than one "different" type.

I agree in principle, but in practice (1) 4758s are still fairly rare in the banking environment and (2) the reason that the 4758 was an interesting device to attack is because the CCA API is far *more* secure than the APIs provided by comparable devices from other vendors. The authors of the crack paper even mention that they've cracked other devices this way. The 4758 was interesting because it's the best of them.

Note, BTW, that I work for IBM and I know the guys who created the 4758, so I have some obvious biases. I also know my way around the boards :) The real weakness uncovered was not in the 4758, but in a thoughtless patch to the 20+ year old CCA API. The "patch" was the addition of 3DES. CCA is the only (AFAIK) formally-designed API for symmetric key management, and it's really well done. When it was created, though, 3DES was unnecessary. It's now obvious that a little more thinking needed to be done when it was "extended" to support 3DES.

This weakness is very easy to close. I don't know what fix they'll choose to implement, but there's a really obvious and simple one: Don't allow a replicate key part (3DES key with identical halves) to be combined with a non-replicate key part to create a non-replicate whole that is an export key.

What I am certain of, though, is that the entire "patched" CCA API is going to be going back to IBM's cryptographers for formal modeling, so that the integrity of the structure can tweaked until the structure can once again be proven to be mathematically correct. This won't happen again; IBM takes security very seriously and has the people that know how to do it.

While I'm on the subject, Linux freaks will be interested to know that the next-generation OS for the 4758 is... Linux! Well, a stripped-down, thoroughly validated version of Linux, anyway. Dunno if the source will be published or not, but I think so. Linux is already running on the boards, but getting the validated version will take some time.

Re:Lessons to be learned:

[Anonymous Coward]

Mod this parent up, he knows exactly what he's talking about

This group has some misconceptions about the FIPS 140 process. First, they rightly point out that the level 4 cert on the IBM 4758 does not cover the CCA software, and then they go on to talk about how a bug in this (admittedly, non-evaluated software) shows the weakness of FIPS 140-1.

Hmm... Well, interesting, but wrong. First, as they point out, the CCA software is not covered by the FIPS cert. Once you install the CCA software on the 4758, the 4758 is no longer a FIPS 140-1 module, level 4 or otherwise. The FIPS cert only applies to the module as it was evaluated. As this post's parent points out, the 4758 allows arbitrary code to be uploaded into the module. This means that as soon as you load unevaluated (ie: non-FIPS 140-1 evaluated) code into the module, it looses its FIPS 140-1 level 4 status.

So, what is evaluated? Examining the NIST FIPS 140 validated modules list you'll see there are several pertinent certificates that apply to the IBM 4758 card. First, there is the level 4 certification of the 4758 and the boot code (Miniboot layers 0 and 1) (certificates # 35 and 116). Next you see the FIPS 140-1 level 3 certificates involving the 4758 with its onboard OS (CP/Q++) at layer 2 (certificates #122, 122). Note that as soon as you add the OS the certification drops to at most level 3. And that's without any application code at all; no CCA, no other libraries, and no applications.

You'll also note, that the CCA is not evaluated under any of these certificates. If you think that this is an oversight on IBM's part, I have a lovely patch of land to sell you.

Now, just to put all this 4758 bashing into perspective: The IBM 4758 is an amazingly secure cryptographic module. It is by far the most well designed and implemented cryptographic module I have ever worked with, and that says a hell of a lot. Sure, there may be more secure modules out there, but not in the civilian market. The 4758 is, to put it plainly, The Shit. The reason this module is such an interesting target is that it defines the state of the art of cryptographic modules. To put it another way, virtually every other cryptographic module (software or hardware) is less secure than the IBM 4758.

When someone demonstrates a possible attack against an IBM 4758, you shouldn't just say to yourself "Oh, this doesn't matter, I don't own/use/deal with one of these". Because the IBM 4758 is the commercial state of the art, the work factor associated with breaking every other cryptographic module out there is less. So, if it only takes an a few days compromise the 4758, it is a fairly good bet that it takes less time than that to compromise any other commercial cryptographic module.

Ain't it grand?

RealVideo Coverage

[guru_steve]

I'm watching the video right now, and its taken a bit of time to find out where this segment is on the bbc news.

So, for those of you who don't feel like jumping around the video for this segment, it starts at about 22 minutes in the broadcast.

Insiders

[Embedded Geek]

I'm glad they pointed out that most thefts are perpetrated by insiders (at banks or other companies) due to the other (physical) security measures. I can only hope that other media outlets don't drop the ball on this and start shouting "hackers can steal your cash" on the 6PM news.

Then again... I guess you'd only need to be an insider at the phone company (or whatever company might be leasing a cable to a phone company) to exploit ATM transfers. You wouldn't need to be a bank employee (who undergo background checks, etc).

ATM's are more prone to stone age methods

[number one duck]

I'm not too worried about this. An electronic fraud is something that can be reasonably gotten out of, its the *banks* fault if their system eats your money. (Admittedly, I haven't read the small print of my own bank, but hey, its not the article, anyway).

The big problem I have with my bank, however, is the location and layout of their ATM machines to begin with:

1) ATM's are built into the wall, rather than in any kind of nook. The line generally forms directly behind the user. (This isn't so much of a problem for e.g. drive through atms, as the bulk of the car is obscuring view of the transaction).

2) The buttons on the keypad are almost two inches across! I know they have to make them 'easy to use', and big happy buttons are important for that, I imagine... but having to move my entire hand around to enter the code makes it trivial to watch someone's movements...as opposed to normal sized buttons where what is being pushed is generally obscured by your hand itself.

3) This is a general problem. Cards are *inserted* rather than *swiped*, which makes it almost trivial for people to rig the machines to prevent the card from being returned. A card swipe, where the card never leaves my hand, would be infinitely preferred to leaving my bank card at the mercy of any hoodlum with a bottle of soap and a pair of pliers.

4) Apparently the ATM card I recieved is more than I asked for... it is also a credit card AND a debit card AND who knows what all else... if they acquire it they can run me down even if I don't have any money left in the account proper.

Question...

[srvivn21]

So they article says that this is really only exploitable by "insiders". At first I felt safe. "Well, at least my money is Federally protected". Then I got to thinking about it. How would I prove that I wasn't the one who used my PIN at an ATM (or several) to clear out my account? Anyone have an answer that can put my mind at ease?
(Not like I'm going to take all my money from the bank, and stuff it in a jar. Just idle thoughts of threat)

Pretty focussed branch manager...

[WasterDave]

"banks are vulnerable to a dishonest branch manager whose teenager has $995 and a few hours to spend in duplicating our work."

If you have a teenager who can hack FPGA's sufficiently well to brute force into a cash machine, you're really not going to have any problems making money in years to come. Either that or your problems are just beginning.

Dave

Only a matter of time

[CmdrTroll]

My brother used to work as a contractor for Cirrus. He said that the PIN encryption was a private joke amongst all of the engineers there. The suits all believed that cryptographic mumbo-jumbo and really expensive chips sold by "connected" salespeople at IBM would protect the banks' assets. But, he said, the problems with the PIN were nearly impossible to solve. Consider:

• The PIN is four decimal digits = 10,000 combinations ~= somewhere between 13 and 14 bits of security. It is entirely feasible for a quick P4 to encrypt every single PIN within an hour, with time left over to play Unreal Tournament.
• There is no trusted path between the user's memory and the bank. Fake ATMs have been installed in shopping malls, collecting PINs and ATM cards from unsuspecting victims. Do you *really trust* every single PIN keypad at every shady gas station, grocery store, and Wal-Mart, not to have logging devices installed? Replay attacks are not rocket science.
• Embedding DES keys inside a chip will inevitably lead to compromise. One needs to look no farther than the DirecTV access cards (particularly the H and F cards) to see the amount of damage that a few determined hobbyists can do. Imagine if there are billions of dollars at stake rather than just a little free TV.

Regardless, this is not a widespread problem. It is a weak system and it was always a weak system. But it's not worth thieves' time to steal PINs yet (for the most part anyway) just because PINless credit card fraud is still so easy.

-CT

Re:Only a matter of time

[WasterDave]

10,000 combinations ~= somewhere between 13 and 14 bits of security. It is entirely feasible for a quick P4 to encrypt every single PIN within an hour, with time left over to play Unreal Tournament.

But if you read their page about how PIN works it becomes aparrent that you still need the derivation key, which is the hard bit to get.

Fake ATMs have been installed in shopping malls, collecting PINs and ATM cards from unsuspecting victims

LOL! Someone did a whole bunch of these in the UK a couple of years ago. Looked and smelled like an ATM, but took the PIN then complained that the card was borked, or something. Easy EASY kill.

because PINless credit card fraud is still so easy.

Exactly. 1e6+1 easier ways of stealing money than opening an ATM with an oxy-acetylene, spending two days cracking it with an FPGA and using all that to hack the banks comms. Easier to just look over some lamers shoulder then pick their pocket. Not that I would know. Not at all.

Dave

Re:Only a matter of time

[Black Acid]

The PIN is four decimal digits = 10,000 combinations ~= somewhere between 13 and 14 bits of security.

For those interested, you can find how many bits a key with x values is using logarithms:

bits = log(x) / log(2), or

bits = d / log(2)

Where d is the number of decimal digits the key is. Therefore, a 4-digit PIN has 4/log(2) or precisely 13.287712379549449391481277717958 bits of cryptographic strength. Not much compared even to weak encryption such as 64-bit DES, or the 56-bit des-ii cracked by d.net.

Is your parent a bank manger?

[Quizme2000]

Until IBM fix the CCA software to prevent our attack, banks are vulnerable to a dishonest branch manager whose teenager has $995 and a few hours to spend in duplicating our work.

I like the tech about hacking the processor, very clever. The rest is better read as bad fiction. Chalk this one up under the anarchist cookbook. Sure you may be able too, but you'll get thrown into jail or blow off a limb.

Some corrections

[hearingaid]

I live in Canada. Some of this may not apply to your jurisdiction.

My bank uses a PIN which is a minimum of 4 digits long. I believe the maximum is 12. This solves the length problem. I have a 4-digit PIN, but that's mainly because I'm a grad student, and anybody who steals my bank card and gives me money has my thanks. Unfortunately, no luck yet. :)

We have Interac cops. Interac is the Canadian banking network; the ATMs you see in malls in Canada are usually run by chartered banks, and when they're not, they're run by somebody on the Interac network. These devices get policed, and they have some pretty serious security measures on them.

There's still the basic vulnerability of the encryption scheme to consider, of course. But the other concerns you bring up can be dealt with.

Related technical paper

[dazed-n-confused]

If you want more technical detail, check out the
paper on API-Level Attacks on Embedded Systems by Mike Bond and Ross Anderson.

Ross Anderson is the author of "Security Engineering" -- if you're interested in this story but haven't read the book, consider this a strong recommendation. More details inc. sample chapters at his website. Plus other fascinating stuff.