The site is getting hugged to death. https://web.archive.org/web/20230724143835/https://lock.cmpx...
Faster link: https://archive.is/QAwvQ
Zenbleed
41–50 of 378 posts
Re: Zenbleed
#42Earlier quoted context omitted.
Huh. The very first line seems pretty clear: > If you remove the first word from the string "hello world", what should > the result be? This is the story of how we discovered that the answer > could be your root password! Can you please expand on your question?
does it require physical access to the machine?
Beyond what everyone else said, these types of exploits can break out of VMs. Unless I'm misreading it you could log into your $5 linode/digitalocean/aws machine and start reading other people's data on the host machine.
There's tons of million dollar/month businesses on ~$20/month accounts on shared machines.
Re: Zenbleed
#43Earlier quoted context omitted.
No, it's all Zen 2 CPUs, which include both desktop CPUs (with or without integrated graphics, laptop CPUs, and server CPUs. The reason why the product list is so confusing is that AMD reuses architectures across generations. You'd think that all ryzen 5000 series CPUs have the same microarchitecture, but they don't). It's much easier to consult this list instead: https://en.wikipedia.org/wiki/Zen_2#Products
FYI this list isn't exhaustive. And I went to recommend the wikichips link and it's not exhaustive either. https://en.wikichip.org/wiki/amd/microarchitectures/zen_2#Al... Both of them are missing the newer 7000-family products with Zen2 like 7520U etc. https://www.amd.com/en/products/apu/amd-ryzen-5-7520u https://www.amd.com/en/products/apu/amd-ryzen-3-7320u https://www.amd.com/en/products/apu/amd-athlon-gold-7220u
The 7520U and 7530U are listed on the linked Wikipedia page. Look under "Ultra-mobile APUs".
The Athlon is missing, though.
Re: Zenbleed
#44This 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 known about by black-hats-for-hire well before they're made public.
CPU vulnerabilities found in the past few years:
https://en.wikipedia.org/wiki/Meltdown_(security_vulnerability)
https://en.wikipedia.org/wiki/Spectre_(security_vulnerability)
https://aepicleak.com/
https://en.wikipedia.org/wiki/Software_Guard_Extensions#SGAxe
https://en.wikipedia.org/wiki/Software_Guard_Extensions#LVI
https://en.wikipedia.org/wiki/Software_Guard_Extensions#Plundervolt
https://en.wikipedia.org/wiki/Software_Guard_Extensions#MicroScope_replay_attack
https://en.wikipedia.org/wiki/Software_Guard_Extensions#Enclave_attack
https://en.wikipedia.org/wiki/Software_Guard_Extensions#Prime+Probe_attack
https://www.vusec.net/projects/crosstalk/
https://en.wikipedia.org/wiki/Hertzbleed
https://www.securityweek.com/amd-processors-expose-sensitive-data-new-squip-attack/Re: Zenbleed
#45Earlier quoted context omitted.
No, it's all Zen 2 CPUs, which include both desktop CPUs (with or without integrated graphics, laptop CPUs, and server CPUs. The reason why the product list is so confusing is that AMD reuses architectures across generations. You'd think that all ryzen 5000 series CPUs have the same microarchitecture, but they don't). It's much easier to consult this list instead: https://en.wikipedia.org/wiki/Zen_2#Products
FYI this list isn't exhaustive. And I went to recommend the wikichips link and it's not exhaustive either. https://en.wikichip.org/wiki/amd/microarchitectures/zen_2#Al... Both of them are missing the newer 7000-family products with Zen2 like 7520U etc. https://www.amd.com/en/products/apu/amd-ryzen-5-7520u https://www.amd.com/en/products/apu/amd-ryzen-3-7320u https://www.amd.com/en/products/apu/amd-athlon-gold-7220u
products/apu/amd-athlon
Wait... now there's also APU's under the AMD Athlon brand? I know that people are happy when AMD's product offerings are on-par or outperforming Intel, but they didn't have to outdo Intel in the consumer confusion arena as well.
Re: Zenbleed
#46No details on the performance impact of the microcode update. Presumably it disables speculative execution of vzeroupper?
Re: Zenbleed
#47Re: Zenbleed
#48The site is getting hugged to death. https://web.archive.org/web/20230724143835/https://lock.cmpx...
It is a simple static HTML page, how is it possible in 2023 a static site could be hugged to death. In most cases HN traffic barely hits 100 page view per second.
It's a security writeup so it's probably run by a security expert who is not an expert at running high traffic websites. Most likely there is something on the page that causes a database hit. Possibly the page content itself.
Re: Zenbleed
#49Relevant 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…
Do they mean "only confirmed on Zen2", or is the problem definitely confined to only this architecture?
Is it likely that this same technique (or similar) also works on earlier (Zen/Zen+) or later (Zen3) cores, but they just haven't been able to demonstrate it yet?
Re: Zenbleed
#50No details on the performance impact of the microcode update. Presumably it disables speculative execution of vzeroupper?
Or adds a guard.
They mention perf issues for the workaround but they're notably absent from the microcode commentary.
I wonder what this is going to do to the new AMD hardware AWS is trying to roll out, which is supposed to be a substantial performance bump over the previous generation.