AMD won't patch all chips affected by severe data theft vulnerability — Ryzen 3000, 2000, and 1000 will not get patched for 'Sinkclose'
tomshardware.com
Here we are - 3600 which was still under manufacture 2-3 years ago are not get patched. Shame on you AMD, if it is true.
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The reason that this is news is because it allows malware to embed itself into the processor microcode once kernel is breached. IE: If it is exploited for compromise, you either have to have the knowledge and hardware to reset the processor microcode manually (Requires an SPI flash tool) or you toss the hardware entirely. There's no just 'blow the drive away and reinstall the OS' solution available.
This sounds weird. I was in the impression that operating systems load updated cpu microcode at every boot, because it does not survive a power cycle, and because the one embedded in the BIOS/UEFI firmware is very often outdated. But then how exactly can a virus persist itself for practically forever?
The OS can't get to the point of loading cpu microcode without that outdated, embedded microcode. The reason it can persist is because there aren't a lot of good ways to see what that UEFI microcode actually is once it's installed. Plus, only the UEFI tells you that it has successfully updated itself. There is no other more authoritative system to verify that against. So the virus could just lie and say it's gone and you would never know. Hence needing to treat it as the worst case scenario, that it never leaves.
And that introduces a specific type of supply chain threat: someone who possesses a computer can infect their own computer, sell it or transfer it to the target, and then use the embedded microcode against the target, even if the target completely reformats and reinstalls a new OS from scratch.
That's not going to affect most people, but for certain types of high value targets they now need to make sure that the hardware they buy hasn't already been infected in the supply chain.
I don’t think it gets to the microcode but the UEFI.