Hardware Backdoors Found in Some x86 CPUs
Hardware backdoors in some x86 CPUs
A researcher has uncovered a hardware backdoor in certain x86 processors, including VIA C3 chips, that allows unprivileged code to bypass protection and access kernel data. The backdoor, enabled by default on some systems, is a hidden non-x86 core that can be activated with a special instruction. The project provides tools to detect and close the vulnerability, along with research on the deeply embedded instruction set.
The rosenbridge backdoor is a small, non-x86 core embedded alongside the main x86 core in the CPU.
- saidnooneever
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...)
- joss82
This backdoor only appears on decades-old VIA C3 embedded x86 processors
- codedokode
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.
- blueflow
As noted by userbinator: https://news.ycombinator.com/item?id=49220030
Not a backdoor, but a documented CPU feature.
The whitepaper about rosenbridge cannot be published because it would constitute scientific fraud.
- bassiee
For Intel-ME and AMD PSP, you fundamentally can't see the backdoor they could produce unless you probe the seperate chip lol.
- rzzzt
You can find recorded presentations on YouTube: https://youtu.be/_eSAF_qT_FY
- sfdlkj3jk342a
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?
- sph
Should add (2018) to the title