Hardware backdoors in some x86 CPUs

this is pretty old by now but still very relevant. people dont look at this enough but with rising chip complexities for TPU units etc. and a shift towards poorly documented hardware like NVIDIA gives this problem new fuel.

Domas (and maybe his team or colleagues?) has put out shit tons of very interesting materials over the past years on advanced malware, implants and things like Cantor Dust which are amazing things to dive into.

using his own cpu fuzzer, msr fuzzing techniques etc. he has found, reversed and implemented attacks through hardware bugs and backdoors.

It cant be confirmed if a backdoor is malicious or for debugging but essentially the capabilities gained through them are what is important.

These techniques he shows throughout his videos are not super tricky to replicate and I can recommend people who have interest to dive into it, reproduce things and try to help in this domain to raise awareness and findings.

Another good avenu is: Defcon 21 - Decapping Chips The Strike Easy Hard Way

People speak about supply chain issues in NPM and Pip etc. but these are much more severe and hard to detect.

Almost no one looks at it. Most vendors totally ignore it because you cannot sell products against it. (if ud detect it u need to trash the hw so its not handy... for sales...)

This backdoor only appears on decades-old VIA C3 embedded x86 processors

This shows that large companies making closed-source CPUs cannot be trusted. No doubt they would add whatever the government asks them to add.

What can be done to mitigate this? One option would be to buy a large FPGA and flash it with an open-source CPU. Another would be to emulate a CPU, working with encrypted data and commands, so that even if the backdoor in a host CPU tries to overwrite memory, it would only crash the emulated OS. One more option would be to run the code in a Virtual Machine like QEMU which translates the code and prevents issuing unknown instructions.

You can find recorded presentations on YouTube: https://youtu.be/_eSAF_qT_FY

So is it apparent that this backdoor was intentionally added by VIA for nefarious purposes? Or is there any other reasonable explanation for its existence?

For Intel-ME and AMD PSP, you fundamentally can't see the backdoor they could produce unless you probe the seperate chip lol.

Should add (2018) to the title

While the README calls it a separate core, it's more likely to be a direct encoding of uops.

"Not this shit again"...

Almost exactly 8 years ago: https://news.ycombinator.com/item?id=17727140

Interesting codenames: https://en.wikipedia.org/wiki/List_of_VIA_C3_microprocessors

Can we add "some ancient Via CPUs" to the title. Current title is pure click bait.