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Bootkit Bypasses TrueCrypt Encryption
mattOzan writes with this excerpt from H-online: "At Black Hat USA 2009, Austrian IT security specialist Peter Kleissner presented a bootkit called Stoned which is capable of bypassing the TrueCrypt partition and system encryption. The bootkit uses a 'double forward' to redirect I/O interrupt 13h, which allows it to insert itself between the Windows calls and TrueCrypt."
TFA has a very good point -- unless you (cryptographically) trust the components of your system all the way down to the hardware itself, you can get pwned by an attack like this. You can regularly do all-the-way-to-the-firmware scrubs of your machine as damage-control, but the only real prophylactic is some form of trusted computing.
Of course, I'm not really dying to jump on the TPM bandwagon, given the sponsors, but it sure would be nice if there was an openly-audited trusted computing module.
I can't tell what's supposed to be interesting or spectacular about this. It's a standard rootkit with MBR support along with some special hooks for truecrypt. It won't let anybody read an encrypted truecrypt volume unless you enter the password... And if you do enter the password on an owned computer it's not like trucrypt is going to help you anywhere. If you unlock the volume any malware can grab all the data it wants through the usual calls and hooks. It doesn't seem especially advanced compared to many of the rootkits out there.
If you care about the privacy of your information then your PC had better be secured at least as well as you would secure your other valuables. If someone can gain physical access to your machine then it's effectively game over.
But that's the entire point of System Encryption right there! Someone gains physical access to your machine and they still can't do squat to read the contents (short of beating you with a hose to get the password or spending serious supercomputer time). System Encryption was designed for precisely this application.
This nice little trick here gives them a third option -- install malware at the BIOS level while leaving TrueCrypt unchanged so as to give you the illusion of safety while they read your mail/keystrokes/whatever. If I were the Border Patrol, I would consider a tool that automates the installation of this tool to be a very worthy investment.
In short, he's exploiting the fact that encryption and authentication are two very different things. TrueCrypt can assure you that you data are unreadable without the key but cannot authenticate the MBR as being genuine. For that, you need some form of trusted computing, the mention of which never goes well.
How does this, in any way shape or form, "break" Truecrypt? Now maybe I misunderstand how it works, since the information is not presented in a clear manner and the author is letting ego get in the way of good writing, but more or less it looks like he has a way to get in to the system at a low level. Ok, great, that does NOTHING to break the encryption. I see nothing in here about managing to get data out of a Truecrypt drive/volume without knowing the key. So what's the big deal?
I mean yes, you could use said malware to log the password. Well guess what? If you've physical access to the system, you don't need software for that. A hardware keylogger would achieve the same thing, or maybe a camera over the shoulder or maybe a tempest attack. The point is if you have physical access to the system, there is little someone can do to keep you from bugging said system.
What Truecrypt is intended to deal with is someone nabbing your system and getting data, and I see no break in that regard. If you encrypt your laptop's harddrive to ensure that nobody gets your data, and somebody steals you laptop, this doesn't help them. For it to help them they'd have to get your laptop, bug it, get it back to you such that you didn't notice, wait for you to use it, then steal it again so they could get the password.
I just fail to see how this is news here. If there is something I'm missing, by all means I'd be interested in knowing.
Giving someone physical access to your machine is the equivalent of losing it and recovering it later, and encryption was never about this case!
Encryption is meant to prevent data release with such a loss, but does nothing much to guarantee integrity of the system after recovery. It does not provide a tamper-evident nor tamper-proof system, since tampering can occur outside the encrypted content. Also, encryption itself does not even provide tamper-proofing for the encrypted volume! It just makes it infeasible to inject known plaintext into the real filesystem, but someone can simply corrupt the ciphertext image and therefore corrupt the real filesystem. You would need additional checksums or other integrity-checks to actually detect such damage.
http://xkcd.com/538/
You're absolutely right. Strangely, none of those links led to Peter Kleissner's web page.
Check out the comments. Some of the visitors are flaming him pretty hard, but he's just a kid with amazing skills and (understandably) very little historical knowledge. Luckily, Christian politely points out that his attack serves to "... alert many people who think they made their PC secure by installing TrueCrypt and still keep working with an admin account where they should not. You prove that a security policy is indispensable, because admin privileges will give malicious software the ability to tamper with the installed security software."