I agree that if these things were by default constantly exfiltrating, say, webcam data, someone would have noticed. But their use is likely much more insidious.

I agree that if these things were by default constantly exfiltrating, say, webcam data, someone would have noticed. But their use is likely much more insidious. Any keyboard event generates some kind of interrupt on x86, right ? Suppose this "ME" happens to record the last 64k keystrokes into a rolling buffer. Furthermore, suppose there is a very, very particular sequence of instructions that can be sent to retrieve this rolling buffer ? Boom. No more encryption (at least none that requires typing a key in from the kb). Oh, you use binary keys ? Cool, intel has special x86 instructions for doing AES. I'm sure they wouldn't do anything like copy the, oh...KEYS, into the hypothetical rolling buffer, would they ? No, that would be "dishonest", and we all know everyone who makes computer hardware and software would never think of doing something so egregiously deceitful, don't we ?