Comment by bflesch

Are you serious?

The CPU firmware blobs are encrypted and nobody except Intel can see what is running there. A handful of people on the planet have the tools and skills to analyze the chip for backdoors.

A small section of CPU cache could stay powered even though the OS is shut down, persisting the keys that were passed to the AES CPU instruction. As CPU is directly linked to wifi/bluetooth and USB chipsets, exfiltration could be possible both wirelessly and via special USB payload.