41–50 of 145 posts
Now the question is "What does the microarchitecture really look like so we can write our own x86 microcode?"
Intel and AMD almost certainly have compilers/assemblers of sorts that handles turning the microcode assembly-of-sorts into the correct bits, but they’re not portable.
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This seems like yet another thing on the list of “x86 hardware issues that sound worse than they are”. I’m interested to see what people are able to reverse engineer with these sorts of tools. It wasn’t even that long ago that ucode wasn’t even encrypted with integrity. I don’t think AMD started doing that until around 2010. I’m also curious which hardware versions this works on, since it’s not obvious it’s universal…
>It wasn’t even that long ago that ucode wasn’t even encrypted with integrity whether they're encrypted or not doesn't really matter. what actually matters is whether they're signed or not. There was a talk given in 2017 about trying to modify the microcode in AMD processors, but they were using processors from a decade ago (AMD K10, introduced 2007). That makes me think that processors made in the past decade are pr…
The followup tweet indicates that the CPU has to be in an unlocked state before this is possible, which on a typical system requires there to be a Management Engine vulnerability first. Given what we currently know, this is going to be interesting for people interested in researching the behaviour and security of Intel CPUs and might well lead to discovery of security issues in future, but in itself I don't think thi…
Plot twist: there’s been a few ME vulnerabilities. And who knows what other purposeful ME backdoors there may or may not be.
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Plot twist: there’s been a few ME vulnerabilities. And who knows what other purposeful ME backdoors there may or may not be.
Sure, which is why this is useful to researchers. But the access someone needs to your system in order to exploit the ME vulnerabilities is sufficiently extreme that if someone achieves it you probably have other things to worry about.
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>It wasn’t even that long ago that ucode wasn’t even encrypted with integrity whether they're encrypted or not doesn't really matter. what actually matters is whether they're signed or not. There was a talk given in 2017 about trying to modify the microcode in AMD processors, but they were using processors from a decade ago (AMD K10, introduced 2007). That makes me think that processors made in the past decade are pr…
Is it this one? https://www.usenix.org/system/files/conference/usenixsecurit...
>Note that Intel started to cryptographically sign microcode updates in 1995 [15] and AMD started to de-ploy strong cryptographic protection in 2011 [15].
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I don't know. It's Windows vs Linux all over; I think Open is better, but Intel has never (AFAIK) pretended to do that. If a customer knows "Intel/Microsoft controls this", I personally feel like that's an acceptable tradeoff. And for people who find that unacceptable, there's Debian on POWER9. But if you're picking Intel, it's not like these opcodes change anything; we already have ME sitting there controlling the m…
Did they release specs so that customer could build their own ME to manage the CPU? That would be interesting.
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Should products be fully documented so that consumers can make an informed decision?
Yes! God, I miss tge days when things actually shipped with manuals on how everything works. I have a fiew old pieces of hardware I keep manuals around for just to remind me of what the writing style is supposed to look like.
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A pen and paper is everything you need.
But what if it’s some of that fancy paper or a pen that records everything you write! Might need to manufacture your own pen and paper now...
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It is public knowledge that US intelligence agencies actually just hijack computers and equipment on their way to the customer and install hardware backdoors there (Snowden et al., 2014). It is also known that they have had backdoors in commercial systems as they came off the shelf, but I think usually those were CIA owned and controlled companies like the crypto AG phones. What is unknown (pure speculation) is wheth…
>What is unknown (pure speculation) is whether, for example, Intel CPUs come backdoored straight from the factory floor? There is also a third possibility, that some intelligence agency invested a ton of cash into finding abusable exploits in these systems giving them the same access a backdoor would provide. Also from the Snowden leaks, we know that they have programs with budgets in the millions into finding simila…
Here is the timestamp