dear Jim and Code Monkey: it is possible to boot from a fob.
the 'boot order' of a linux bias might be most interesting. I've always imagined that the mother boards themselves or even the 'usb connectors' could also be compromised. Other items: powersupplies and LED stripes too.
any of these could have wireless aspects that are undocumented and secret.
you could even manifest it into a wire or connector.
How do those machines boot.
can you do a silent and secret boot of them by inserting a fob?
a printer, a phone, anything that would be 'discovered' , can be hijacked to do all kinds of root privledge stuff if you set it up to do that.