Retbleed: Your x86 Speculative Attack Du Jour

Jul 12, 2022 @ 6:29 pm

Retblood “Today Intel released two security advisories addressing 2 medium severity vulnerabilities reported by academic researchers from ETH Zurich who have labeled their side-channel attack as “Retbleed” due to finding a method to potentially bypass a commonly used mitigation technique known as retpoline.”

That’s what Intel said on their blog but the Ars Technica article sure makes this sound more serious than “medium”. According to Ars Technica:

Retbleed can leak kernel memory from Intel CPUs at about 219 bytes per second and with 98 percent accuracy. The exploit can extract kernel memory from AMD CPUs with a bandwidth of 3.9 kB per second. The researchers said that it’s capable of locating and leaking a Linux computer’s root password hash from physical memory in about 28 minutes when running the Intel CPUs and in about 6 minutes for AMD CPUs.

So if I can run code on an x86 server and recover the root password in less than half an hour…that is not medium.

And fixing this could cost up to a 28% performance overhead. Ouch.

Patch up!

There is a white paper available. Unfortunately, no cool logo yet.

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raindog308

Dread Lord of LowEnd Content at LowEndBox

I'm raindog308, techno polymath and long-time LowEndTalk community Administrator. My technical interests include all things Unix, perl, python, golang, shell scripting, vintage operating systems such as MVS, and relational database systems such as Oracle, PostgreSQL, and MySQL.

I also enjoy using LEBs! I have an empire of little guys for VPNs, larger guys for apps, and big guys for databases and storage. When I'm not in front a screen I'm into German Shepherd dogs, quality knives, target shooting, theology, tabletop roleplaying games, and forest hiking.

I enjoy writing technical articles here on LowEndBox to help people get more out of their systems. You can find me on LowEndTalk @raindog308