Hardware Rootkits:

Hardware Rootkits are Rootkits that can reside on
the Hardware of a computer, that means not in the
Hard disk.The Rootkits can reside in the BIOS or
some form of Memory on the Main Board.

Most of us wouldn't know that even the Processor
in our Computer gets updated.Probably this
could be one place where the Rootkit could hide.

A lot of computer parts are manufactured in China
and some articles on the net speculate that the parts
assembled in China could have embedded Rootkits.

A lot of computer parts and accessories such as
Modems, Routers,Display cards have some place
where information is stored to enable the device
to function. This Software for these Hardware
devices is called Firmware,which could be infected.