NSA back door and other foreign intel agencies and of course hackers.
“Once a system is compromised by a rootkit, attackers can gain administration access and undetectably attack the computer.”
People give hackers too much credit
Exactly what it appears to be... NSA’s “back-door” since the hidden CPU acts as a TCP/IP server functioning even when the computer is in a sleep/power conservation mode. It’s encrypted, so somebody has the keys.