Feeds

Security boffins attempt to freeze out cold boot crypto attack

Cache from chaos

Beginner's guide to SSL certificates

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. ®

Protecting users from Firesheep and other Sidejacking attacks with SSL

More from The Register

next story
Spies would need SUPER POWERS to tap undersea cables
Why mess with armoured 10kV cables when land-based, and legal, snoop tools are easier?
Early result from Scots indyref vote? NAW, Jimmy - it's a SCAM
Anyone claiming to know before tomorrow is telling porkies
Apple Pay is a tidy payday for Apple with 0.15% cut, sources say
Cupertino slurps 15 cents from every $100 purchase
Israeli spies rebel over mass-snooping on innocent Palestinians
'Disciplinary treatment will be sharp and clear' vow spy-chiefs
YouTube, Amazon and Yahoo! caught in malvertising mess
Cisco says 'Kyle and Stan' attack is spreading through compromised ad networks
Hackers pop Brazil newspaper to root home routers
Step One: try default passwords. Step Two: Repeat Step One until success
China hacked US Army transport orgs TWENTY TIMES in ONE YEAR
FBI et al knew of nine hacks - but didn't tell TRANSCOM
Microsoft to patch ASP.NET mess even if you don't
We know what's good for you, because we made the mess says Redmond
NORKS ban Wi-Fi and satellite internet at embassies
Crackdown on tardy diplomatic sysadmins providing accidental unfiltered internet access
prev story

Whitepapers

Providing a secure and efficient Helpdesk
A single remote control platform for user support is be key to providing an efficient helpdesk. Retain full control over the way in which screen and keystroke data is transmitted.
WIN a very cool portable ZX Spectrum
Win a one-off portable Spectrum built by legendary hardware hacker Ben Heck
Saudi Petroleum chooses Tegile storage solution
A storage solution that addresses company growth and performance for business-critical applications of caseware archive and search along with other key operational systems.
Protecting users from Firesheep and other Sidejacking attacks with SSL
Discussing the vulnerabilities inherent in Wi-Fi networks, and how using TLS/SSL for your entire site will assure security.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.