This will be very interesting!
https://fossbytes.com/game-over-intels-me-chip-can-be-hacked-over-usb/
#Update 12/29/2017 https://www.blackhat.com/docs/eu-17/materials/eu-17-Goryachy-How-To-Hack-A-Turned-Off-Computer-Or-Running-Unsigned-Code-In-Intel-Management-Engine-wp.pdf