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AMD have released an microcode update for affected processors. Your BIOS or Operating System vendor may already have an update available that includes it. I don’t really understand how CPU microcode updates work. If I’m keeping Ubuntu up to date, will this just happen automatically?
microcode changes are provided to the CPU at boot time and are only valid early in the boot process. the machine UEFI/BIOS must apply them.
AMD have released an microcode update for affected processors. Your BIOS or Operating System vendor may already have an update available that includes it. I don’t really understand how CPU microcode updates work. If I’m keeping Ubuntu up to date, will this just happen automatically?
no. microcode changes are provided to the CPU at boot time and are only valid early in the boot process. the machine UEFI/BIOS must apply them.
This is super cool. This exploit will be one of the canonical examples that just running something in a VM does not mean it's safe. We've always known about VM breakout, but this is a no-breakout massive exploit that is simple to execute and gives big payoffs. Remember: just because this one bug gets fixed in microcode doesn't mean there's not another one of these waiting to be discovered. Many (most?) 0-days are kno…
In the case of the VM won't registers be wiped when entering/exiting the VM?
Relevant snippet: This technique is CVE-2023-20593 and it works on all Zen 2 class processors, which includes at least the following products: AMD Ryzen 3000 Series Processors AMD Ryzen PRO 3000 Series Processors AMD Ryzen Threadripper 3000 Series Processors AMD Ryzen 4000 Series Processors with Radeon Graphics AMD Ryzen PRO 4000 Series Processors AMD Ryzen 5000 Series Processors with Radeon Graphics AMD Ryzen 7020 S…
and how about playstation 5 ? and also xbox and that thing from valve?
0 - https://blog.playstation.com/2020/03/18/unveiling-new-detail...
Why does disabling SMT not fully prevent this? I don't know the details of Zen 2 architecture, but register files are usually implemented as SRAM on the CPU-die itself. So unless the core is running SMT, I don't understand how another thread could be accessing the register file to write a secret.
So even with SMT disabled, each core will execute sequentially many threads, switching every few milliseconds from one thread to another, and each context switch does not modify the hidden registers, it just restores the architecturally visible registers.
This is super cool. This exploit will be one of the canonical examples that just running something in a VM does not mean it's safe. We've always known about VM breakout, but this is a no-breakout massive exploit that is simple to execute and gives big payoffs. Remember: just because this one bug gets fixed in microcode doesn't mean there's not another one of these waiting to be discovered. Many (most?) 0-days are kno…
In the end, I'm thinking most of these are related to branch prediction? It strikes me that it's either that branch prediction is so inherently complex enough it's always going to be vulnerable to this and/or it just so defies the way most of us intuitively think about code paths / instruction execution that it's hard to conceive of the edge cases until too late? At what point does the complexity of CPU architectures…
Earlier quoted context omitted.
Is apt update && apt upgrade enough for pop-os users?
Probably eventually yes, but if you are really concerned you need to discuss it with your distro maintainers.
This is incredibly scary. On my Zen 2 box (Ryzen 3600) logging the output of the exploit running as an unprivileged user while copying and pasting a string into a text editor in the background (I used Kate), resulted in pieces of the string being logged into the output of zenbleed. And this is after a few seconds of runtime mind you, not even a full minute. Thankfully the exploit is highly dependent on a specific asm…
At least one commentor here claims to be able to reproduce this with javascript: https://news.ycombinator.com/item?id=36849767 .
AMD have released an microcode update for affected processors. Your BIOS or Operating System vendor may already have an update available that includes it. I don’t really understand how CPU microcode updates work. If I’m keeping Ubuntu up to date, will this just happen automatically?