Posted on 02/22/2008 8:20:54 AM PST by ShadowAce
The disk encryption technology used to secure the data in your Windows, Apple and Linux laptops can be easily circumvented, according to new research out of Princeton University.
The flaw in this approach, the researchers say, is that data previously thought to disappear immediately from dynamic RAM (DRAM) actually takes its time to dissolve, leaving the data on the computer vulnerable to thievery regardless of whether the laptop is on or off. That's because the disk encryption key, unlocked via a password when you log on to your computer, then is held in DRAM. If a thief can get a hold of the key, he can then get into the disk.
"We demonstrate our methods by using them to defeat three popular disk encryption products: BitLocker, which comes with Windows Vista; FileVault, which comes with MacOS X; and dm-crypt, which is used with Linux," writes Ed Felten, a Princeton professor, on his blog, Freedom to Tinker.
The researchers, which also included participants from the Electronic Frontier Foundation and Wind River Systems, have created a captivating video demonstrating a process (one using a program dubbed "Bit-unLocker") that can be used to snatch the data. In the video, the narrator explains that it takes seconds for data to fade and that the process can be slowed by cooling the memory chips (they chill the memory chips to around -58 F with a liquid spray and remove them without affecting the contents). The chips can even be switched to a different computer to read them. Liquid nitrogen can be used to cool the chips for hours, the researchers say.
"This is deadly for disk encryption products because they rely on keeping master decryption keys in DRAM," Felten writes.
Felten adds that even using Trusted Computing hardware doesn't help.
(A presentation from a pair of security researchers scheduled for Black Hat USA last summer that promised to undermine chip-based desktop and laptop security was suddenly withdrawn without explanation. The briefing promised to show how computer security based on trusted platform module hardware could be circumvented.)
The Princeton findings prompted Steven Sprague, CEO of Wave Systems, which makes management software for hardware security devices, to point out that such attacks on laptops would be preventable via hardware-based encryption offerings.
"The advantage of hardware-based encryption is that all the encryption, key management and access control all happen inside the chip so there is no software risk to reverse engineer the encryption silicon," Sprague said. The encryption key never leaves the hardware-based encryption disk in this case, he said.
Members of the Dataloss@attrition.org mailing list, which daily documents data breaches, buzzed about the findings, with some suggesting the research shows the need for multifactor authentication or partial keys stored in separate places.
U.S. states have enacted a series of tough data disclosure laws over the past five years which force companies to notify residents whenever they lose sensitive information. Under these laws, a missing laptop can cost a company millions of dollars as well as public embarrassment as it is forced to track down and notify those whose data was lost.
However, many state laws, such as California's SB 1386 make an exception for encrypted PCs. So if a company or government agency loses an encrypted laptop containing sensitive data, they are not compelled to notify those affected.
The team's research may spur legislators to rethink that approach, according to Alex Halderman, a Princeton graduate student who worked on the paper. "Maybe that law is placing too much faith in disk encryption technologies," he said. "It may be that we're not hearing about thefts of encrypted machines where that data could still be at risk."
Shouldn’t be too hard to have the BIOS write pseudo-random data to the DRAM as a last step in shut-down, no?
Or even zeros, since they’re reading the inferred data value not the DRAM cell charge itself.
According to the article, the chips have to be cooled within seconds of the system shutting down to be able to recover the key from DRAM. That essentially means someone would have to steal a laptop that is still running to get the key. I’m not sure how big of a vulnerability this is in the real world.
Does this only apply to hardwired desktops? What happens if I kill my wireless on my laptop before suspending?
Yeah, the moral of the story is if you see someone you don’t know with a dewar of LN2 and a screwdriver hanging around your computer, you should become suspicious...
You'd likely get the same effect today by rebooting with a bootable CD or USB drive.
See #8.
Now there's an understatement. ;-)
I think the rest of the moral is that the people who spent time figuring out that if you yank out a chip, within .73 seconds dip it in liquid nitrogen, 43 seconds later install it in a new machine, run some specialized software, you MIGHT be able to unencrypt something.
These folks need jobs.
Real jobs.
That's my point - unless they grab a running machine or grab the machine within a few seconds of being shut down, this isn't that much of a vulnerability. For 99% of users, using the disk encryption will be sufficient. For government agencies or companies that have a lot of financial data on their laptops, which might be targeted by professional thieves or foreign governments, they may need to be concerned.
Really out-of-the-realm-of-possibility security vulnerability discovered in encrypted disks on both Apple OS X and Windows Vista...
If you want on or off the Mac Ping List, Freepmail me.
We’re starting to develop a real “Boy who cried wolf” phenomena with the security people. I guess it’s like everything else. You’d better have someone translate. I consider myself fairly computer literate, but I had no clue whether it was a risk or not, until I realized you had to get the actual physical computer. I kind of figure if somebody gets the computer, they can probably figure out a way to get information out of it.
Watch out for cryogenic data pirates!
Moral of the story: there are no perfect locks, only perfect fools that trust in them.
This requires physical access to the computer and fairly extra-ordinary methods (chilling the RAM to -54 degrees, removing it, putting in another computer, and read). While I won’t say that folks wouldn’t go through that for data, I believe it would likely be an extraordinary case - like national security or BIG bucks. And I believe that such extreme cases would probalby also involve more serious security protection than what comes “stock” on those computers.
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