Feeds

Security boffins attempt to freeze out cold boot crypto attack

Cache from chaos

SANS - Survey on application security programs

Security researchers have developed prototype countermeasures to defend against the recently developed cold boot crypto attack.

Cold boot is a technique for snatching cryptographic keys from memory, creating a means to circumvent disk encryption. A targeted machine that's been left hibernating would be turned off and quickly rebooted using an external hard drive, loaded with customised software, in order to extract encryption keys stored in memory.

The technique works because DRAM circuits used in modern PCs retain data for a short time after they are powered down, contrary to popular opinion. Cold boot attacks are of potential interest to both hackers and computer forensics experts.

Crypto boffins are on the way to defending against the attack. By saving cryptographic keys in CPU cache, instead of potentially vulnerable DRAM, the attack can potentially be frustrated.

"By switching the cache into a special mode one can force that data remains in the cache and is not written to the backing RAM locations," write the security researchers behind the Frozen Cache blog. "Thus, the encryption key can't be extracted from RAM. This technique is actually not new: LinuxBIOS/CoreBoot calls this Cache-as-RAM. They use it to allow "RAM access", even before the memory controller is initialized."

The researchers have developed a proof-of-concept implementation of the defence that works under Linux but many problems remain, particularly in recovering from hibernation.

"Disabling/freezing the CPU's cache severely degrades the performance," the researchers write.

"However, this seems acceptable if one considers that this special mode only needs to be set whenever the screen is locked (all efforts are pretty much worthless if an unlocked laptop is stolen). A very first proof-of-concept test on Linux shows that there's quite a bit of performance optimization necessary to make even just the act of unlocking the GUI an acceptable experience (from a performance/usability perspective)."

Other factors, such as developing an approach for machines with multi-core CPUs, as well as optimisation (fine-tweaking) problems remain to be addressed. Interested parties can follow the evolution of the idea through the Frozen Cache blog here. ®

High performance access to file storage

More from The Register

next story
Obama allows NSA to exploit 0-days: report
If the spooks say they need it, they get it
Putin tells Snowden: Russia conducts no US-style mass surveillance
Gov't is too broke for that, Russian prez says
Snowden-inspired crypto-email service Lavaboom launches
German service pays tribute to Lavabit
Mounties always get their man: Heartbleed 'hacker', 19, CUFFED
Canadian teen accused of raiding tax computers using OpenSSL bug
One year on: diplomatic fail as Chinese APT gangs get back to work
Mandiant says past 12 months shows Beijing won't call off its hackers
Heartbleed exploit, inoculation, both released
File under 'this is going to hurt you more than it hurts me'
Arts and crafts store Michaels says 3 million credit cards exposed in breach
Meanwhile, Target investigators prepare for long process in nabbing hackers
prev story

Whitepapers

SANS - Survey on application security programs
In this whitepaper learn about the state of application security programs and practices of 488 surveyed respondents, and discover how mature and effective these programs are.
Combat fraud and increase customer satisfaction
Based on their experience using HP ArcSight Enterprise Security Manager for IT security operations, Finansbank moved to HP ArcSight ESM for fraud management.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
Top three mobile application threats
Learn about three of the top mobile application security threats facing businesses today and recommendations on how to mitigate the risk.
3 Big data security analytics techniques
Applying these Big Data security analytics techniques can help you make your business safer by detecting attacks early, before significant damage is done.