Hi Coins,

I'm not coreboot, but I'm a part of it, so I will try to answer your
question. CCing the coreboot mailing list for more input, as I can only
assume that that list was the intended recipient for your email.

It is unproven that Intel deliberately builds in backdoors into their
CPUs. However, a lot of their software / hardware designs create a
rather large attack surface that could be exploited, if someone puts the
right amount of resources on the problem.

This attack surface lives
 
- in the SOC's converged security management engine (CSME / ME), which
  in some SKUs enables remote access to the system through builtin
  network interfaces. The CSME cannot be fully disabled, but some
  security issues can be mitigated in a good hardware software design
  i.e. by using the non-enterprise (aka 1.5M SKU) of the ME firmware or
  by not using the SOC associated network interfaces (questionable) or
  by disabling as many CSME features as possible.
  CSME is particularly problematic because it can access main memory, so
  a remote attack could steal your private keys, rendering your
  cryptographical secrets useless.

- FSP / BLOBS. Closed source firmware pieces generally have the problem
  that they are impossible to audit. Even if there are fixed version out
  in the field, you can not tell from a binary what is fixed or not.
  Bugs are also impossible to fix, even when known. Imaginable attack
  scenarios could also be deliberate changes to memory training data
  which open known but fixed memory controller issues.

Generally coreboot tries to enable the user / developer / systembuilder
to address as many of these concerns as possible, but it can not 100%
fix them at this point. If you are concerned about your hardware
architecture, please study the source code of coreboot and the available
open documentation on x86 hardware (of which there is a fair amount) and
help us audit our code.

Stefan



* Coins <co...@cryptolab.net> [190331 18:29]:
> Dear Coreboot,
> 
> As far as I know, Intel puts proprietary backdoors in any recent CPU they
> develop.
> 
> How does this affect the security of a PC/laptop with coreboot installed
> when it is using such a processor?
> 
> Best regards,
> 
> 
> Coins
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