Intel ME is a microcontroller, and part of
Intel's AMT hardware and firmware technology which allows administrators to remotely manage the hardware over network – all underneath whatever operating system is running. As this management is conducted at a low-level in the stack, it dodges the OS – meaning overwriting your out-of-the-box Windows installation with a Linux distro will not guarantee any trustworthiness.
The ME microcontroller comes with its own RAM, it can access the system's RAM, and it has its own private ROM of firmware code, which nobody may inspect. “It runs a whole bunch of proprietary programs,” said Rutkowska, “and even runs Intel's own proprietary operating system, and this is all happening whenever you have some power connected to your processor, even in sleep mode, and it could be doing anything it wants.”