Attack detectors on CPUs expose backdoors

How can you be sure that the CPU on your computer hasn’t been tampered with and is not stealthily collecting your data for someone else to use?

Adam Waksman and Simha Sethumadhavan, two scientists from Columbia university, have presented TrustNet and DataWatch – lightweight attack detectors that are incorporated into the microprocessor and issue alerts when it executes an unexpected amount of instructions or shows signs of being modified for malicious purposes.

“Our mechanisms leverage the fact that multiple components within a microprocessor must necessarily coordinate and communicate to execute even simple instructions, and that any attack on a microprocessor must cause erroneous communications between microarchitectural subcomponents used to build a processor,” say the two scientist in their paper.

They tested the two detectors on a Sun Microsystems’ OpenSPARC T2 processor and say that all emitter and control corrupter attacks have been detected, and that no false positives or false negatives emerged during testing. They also point out that they “protect pipelines and on-chip cache hierarchies at negligible area cost and with no performance impact.”

“The root of trust in all software systems rests on microprocessors because all software is executed by a microprocessor,” say the researchers. But, implicitly trusting our hardware has become difficult. “Increasing use of third-party “soft” intellectual property components, the global scope of the chip design process, increasing processor design complexity and integration, the growing size of processor design teams and the dependence on a relatively small number of designers for a sub-component, all make hardware highly susceptible to malicious design. A sufficiently motivated adversary could introduce backdoors during hardware design,” they say.

And they are right. An article by Engineering & Technology revealed a couple of days ago that the issue of counterfeit consumer electronics or components has seriously affected global trade and has cast the shadow of a doubt over the trustworthiness of devices and components we use – microprocessors included.

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