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A newly discovered security vulnerability in modern Intel and AMD processors could let remote attackers steal encryption keys via a power side channel attack.

Dubbed Hertzbleed by a group of researchers from the University of Texas, the University of Illinois Urbana-Champaign, and the University of Washington, the issue is rooted in dynamic voltage and frequency scaling (DVFS), a power and thermal management feature employed to conserve power and reduce the amount of heat generated by a chip.

“The cause is that, under certain circumstances, periodic CPU frequency adjustments depend on the current CPU power consumption, and these adjustments directly translate to execution time differences (as 1 hertz = 1 cycle per second),” the researchers said.

This can have significant security implications on cryptographic libraries even when implemented correctly as constant-time code to prevent timing-based side channels, effectively enabling an attacker to leverage the execution time variations to extract sensitive information such as cryptographic keys.

images from Hacker News