said by trparky:If the OS is already loaded, there's not much the BIOS/UEFI can do because the OS already has control over the Ethernet controller.
Not strictly true, at all. See Intel vPro, it has, among many other powerful features, a VNC server that runs
entirely within the UEFI itself, full time, completely independent of any OS, even allowing full system access and control whether the OS is running or not.