wired New ‘Retbleed’ Attack Can Swipe Key Data From Intel and AMD CPUs

[UltraMega]

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The ETH Zurich researchers have conclusively shown that retpoline is insufficient for preventing speculative execution attacks. Their Retbleed proof-of-concept works against Intel CPUs with the Kaby Lake and Coffee Lake microarchitectures as well as with AMD Zen 1, Zen 1+, and Zen 2 microarchitectures.

 

“Retpoline, as a Spectre-BTI mitigation, fails to consider return instructions as an attack vector,” researchers Johannes Wikner and Kaveh Razavi wrote. “While it is possible to defend return instructions by adding a valid entry to the RSB return stack buffer before executing the return instruction, treating every return as potentially exploitable in this way would impose a tremendous overhead. Previous work attempted to conditionally refill the RSB with harmless return targets whenever a perCPU counter that tracks the call stack depth reaches a certain threshold, but it was never approved for upstream. In the light of Retbleed, this mitigation is being re-evaluated by Intel, but AMD CPUs require a different strategy.”

New ‘Retbleed’ Attack Can Swipe Key Data From Intel and AMD CPUs | WIRED

WWW.WIRED.COM

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The exploit can leak password information and other sensitive material, but the chipmakers are rolling out mitigations.

 

Here we go again. 

[Diffident]

The mitigations are performance killers...at least on Linux.

 

Benchmarking The Linux Mitigated Performance For Retbleed: It's Painful

WWW.PHORONIX.COM

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Yesterday Retbleed was made public as a new speculative execution attack exploiting return instructions.

 

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The Linux mitigation for Retbleed is invasive at nearly two thousand lines of new code and nearly 400 lines removed, across dozens of files. In the Retbleed whitepaper by ETH Zurich COMSEC researchers, they characterized the mitigations as result in 14~39% overhead. I've been testing the Linux patches out on various systems locally and indeed it's quite severe. The Retbleed mitigations are some of the most performance-wrenching mitigations I've seen in a few years going back to the early Spectre/Meltdown days.

[Sir Beregond]

2 hours ago, Diffident said:

The mitigations are performance killers...at least on Linux.

 

Benchmarking The Linux Mitigated Performance For Retbleed: It's Painful

WWW.PHORONIX.COM

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Yesterday Retbleed was made public as a new speculative execution attack exploiting return instructions.

 

Yikes. Here we go again indeed, but even worse.

[bonami2]

Moore law is here and now we get security issue every month that reduce performance kinda funny.

 

Amd adding chiplet to gpu to increase performance while the tech was ready there 10 year ago with the 7990

Edited July 17, 2022 by bonami2