Once you find a bug in certain critical paths, you can write to flash at will, no signatures required. AFAICS some Samsung and Lenovo users ran into one of those when installing Linux.
As for the management engine (the CPU that drives the vPro stuff), it exists in _all_ Intel chipsets since Series 5, vPro is just a certain configuration of its firmware. It also has full access to RAM, some access to USB, network and graphics.
As for the management engine (the CPU that drives the vPro stuff), it exists in _all_ Intel chipsets since Series 5, vPro is just a certain configuration of its firmware. It also has full access to RAM, some access to USB, network and graphics.