Undocumented x86 instructions in Intel CPUs that can modify microcode

Re:Undocumented x86 instructions in Intel CPUs that can modi... by vlovich123 on Saturday March 20, 2021 @12:49PM (#26524327)

I’m not saying that’s the case here, but that’s the general problem with the line of reasoning that “hey if you already have permission X then doing Y is the least of your concerns”.

The concept of defense in depth literally relies on each barrier being independent and robust. That’s why you see hardening of Linux’s hibernate even though the common refrain is “well if you have physical access the game is lost”. There are things that even root can’t do even though “hey if you have root the game is lost”. The point of the game is to never lose even in very adverse environments.

[ Parent | on HN ]

Re:Undocumented x86 instructions in Intel CPUs that can modi... by mjg59 on Saturday March 20, 2021 @01:06PM (#26524437)

The assumption on Intel is that there are no barriers once you're in the ME. You can't defend against a hostile ME. The security model is already violated. Maybe there should be a barrier between the ME and the CPU, but as can be seen here Intel feel that the ME should be in a position to put the CPU in debug mode so shrug.

[ Parent | on HN ]

Re:Undocumented x86 instructions in Intel CPUs that can modi... by EE84M3i on Sunday March 21, 2021 @01:39AM (#26528348)

Where can I read about "hardening of Linux’s hibernate"? I'm curious

[ Parent | on HN ]

Re:Undocumented x86 instructions in Intel CPUs that can modi... by mjg59 on Sunday March 21, 2021 @02:23AM (#26528505)

https://mjg59.dreamwidth.org/55845.html

[ Parent | on HN ]