Researchers develop simple attack against disk encryption

From Boing­Bo­ing comes the most dis­turb­ing infor­ma­tion secu­rity news I have read in a while.

We’ve long assumed that disk encryp­tion is a robust means of stor­ing con­fi­den­tial data on a com­puter. Disk encryp­tion prod­ucts work by encrypt­ing all of the data on a drive, includ­ing doc­u­ments, the oper­at­ing sys­tem, swap files and caches. Disk encryp­tion soft­ware can start up before the oper­at­ing sys­tem to let the user enter their pass­word or key. Disk encryp­tion soft­ware can also be used on USB stor­age, as well as par­ti­tions on an unen­crypted drive.

Disk encryp­tion helps trav­el­ers keep their data con­fi­den­tial. My post of 5 Janaury 2008 addresses how cryp­tog­ra­phy works.

Warm RAM, lost key

Prince­ton Uni­ver­sity researchers have devel­oped a sim­ple attack that can retrieve the Bit­Locker disk encryp­tion key from a Win­dows Vista com­puter. The user has to have logged into the com­puter so that the encryp­tion key is then stored in the computer’s RAM. If the com­puter is in sleep mode, run­ning a screen saver, or still warm, the encryp­tion key can be extracted from RAM. The extracted data can be saved to a USB stor­age device, so that another com­puter can take its time to ana­lyze and fix any errors in the extracted key.

The same kind of attack will also work on Apple Fil­e­Vault, True­Crypt, PGP Whole Disk Encryp­tion, and other disk encryp­tion prod­ucts. The research report is avail­able as a PDF file at this web site.

Declan McCul­lagh has posted his analy­sis of the report at news.com. he points out that this vul­ner­a­bil­ity has been used by other researchers to pull data through a FireWire con­nec­tion to an iPod. It is dif­fi­cult to harden a com­puter against this form of attack, but the attack must be car­ried out in per­son. It can­not be done across the Inter­net, at least in the form that the researchers demon­strate. The attacker needs a USB drive pre­loaded with the attack soft­ware. A can of Dust-Off might also be help­ful, to chill the RAM.

Watch that drive

The eas­i­est way to harden a com­puter against this attack is to main­tain phys­i­cal con­trol of the encrypted drive. Don’t leave it alone. Update the encryp­tion soft­ware reg­u­larly, as the soft­ware devel­op­ers will more than likely develop their own patches to wipe the key from RAM.
This YouTube video pro­duced by the research team is a brief overview of the vul­ner­a­bil­ity and the attack.

Tagged as: crime, crypto, hardware, iPod, Microsoft, security, software, storage, USB, Windows