05 March 2010 | 10,227 views

Boffins Crack OpenSSL Library Using Power Fluctuations

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Now this is a very interesting technique, as far as I know I’ve not seen anything similar to this before. It’s like a rather bizarre meld of hardware hacking and software exploitation using cryptographic algorithm cracking techniques.

Some rather smart fellas have found a way to extract the private SSL key from a device by creating fluctuations in the power supply and reading the output whilst the device was encrypting data using the private key.

In around 100 hours they could deduce the complete 1024-bit private key stored on the device.

Computer scientists say they’ve discovered a “severe vulnerability” in the world’s most widely used software encryption package that allows them to retrieve a machine’s secret cryptographic key.

The bug in the OpenSSL cryptographic library is significant because the open-source package is used to protect sensitive data in countless applications and operating systems throughout the world. Although the attack technique is difficult to carry out, it could eventually be applied to a wide variety of devices, particularly media players and smartphones with anti-copying mechanisms.

“Wherever you need to verify the origin of a piece of software or a piece of information, those building blocks come in handy,” said Karsten Nohl, an independent security researcher who in unrelated attacks has broken encryption in widely used smartcards and cordless phones. “The OpenSSL library provides much more than just SSL.”

Now although this flaw can be deemed extremely serious and the number of applications and operating systems that use OpenSSL is huge…the fact that they need physical access to the device the manipulate the power supply means the scope of the attack is limited.

It’s not something you could pull off on a remote server in a data center for example.

It would be interesting however for cracking private keys on consumer hardware devices to access the private network that the device hooks onto for updates/subscription packages etc.

The scientists, from the University of Michigan’s electrical engineering and computer science departments, said the bug is easily fixed by applying cryptographic “salt” to an underlying error-checking algorithm. The additional randomization would make the attack unfeasible. An OpenSSL official, who asked that his name not be published, said engineers are in the process of pushing out a patch and stressed the attack is difficult to carry out in real-world settings.

The university scientists found that they could deduce tiny pieces of a private key by injecting slight fluctuations in a device’s power supply as it was processing encrypted messages. In a little more than 100 hours, they were able to feed the device enough “transient faults” that they were able to assemble the entirety of its 1024-bit key.

“This is probably not as much of a threat to a server system as it is to a consumer device,” said Todd Austin, one of the scientists who devised the attack. “The place where this would be more applicable would be if you want to attack a Blu-ray player (where) you have an environment where someone is giving you a device that has a private key to protect intellectual property and you have physical access to the device.”

But as per usual for cryptographic attacks, they are usually researched and developed by scientists and work in the theoretical realm far better than they do in reality for practical exploitation.

Either way it’s an interesting attack and an interesting use of technology, of course OpenSSL will be patching the problem shortly (adding a simple salt will negate the attack).

What will they come up with next?

Source: The Register



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2 Responses to “Boffins Crack OpenSSL Library Using Power Fluctuations”

  1. Tim 5 March 2010 at 1:27 pm Permalink

    Can this attack be modified to send fake packets to a web server while it is encoding an SSL message (this causing those transient faults)?

    I doubt any sessions last for 100 hours though.

  2. Capt_wheeto 6 March 2010 at 1:40 pm Permalink

    ‘Boffins’ made me lol. Always interesting to hear about vulnerabilities that aren’t limited to just software. I wonder if this attack has actually been pulled off in the wild