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New "BranchScope" Side-channel CPU Vulnerability Threatens Modern Processors

In the age of cyber-security vulnerabilities being named by their discoverers, much like incoming tropical storms, the latest, which exploits speculative execution of modern processors, is named "BranchScope," discovered by academics from four US universities, Dmitry Evtyushkin, Ryan Riley, Nael Abu-Ghazaleh, and Dmitry Ponomarev. The vulnerability has been successfully tested on Intel "Sandy Bridge," "Haswell," and "Skylake" micro-architectures, and remains to be tested on AMD processors. It bears similarities to "Spectre" variant 2, in that it is an exploit of the branch prediction features of modern CPUs.

BranchScope differs from Spectre variant 2, in that while the latter exploits the branch target buffer, BranchScope goes after the directional branch predictor, a component that decides which speculative operations to execute. By misdirecting it, attackers can make the CPU read and spit out data from the memory previously inaccessible. The worst part? You don't need administrative privileges to run the exploit, it can be run from the user-space. Unlike CTS-Labs, the people behind the BranchScope discovery appear to have alerted hardware manufacturers significantly in advance, before publishing their paper (all of it, including technicals). They will present their work at the 23rd ACM International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLOS 2018), later today.
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