The DMA attack is based on a "feature" of firewire which gives it
direct read/write access to memory.
"DMA as most of you probably know is a feature used to speed up
access to memory by bypassing the processor, this is needed for
instance by graphic cards which do their own processing on data in
memory. It's a great enhancement to allow for speedy input/output
of data where the main processor is not needed. The firewire
protocol allows external devices to directly access memory for
read/write operations. This makes it easily possible to change data
in system memory using an external device (like a modified ipod for
This can give you root access to a running Linux system as long as
it has a working firewire port. You can read more about this
specific security flaw as well as methods of mitigating it here
(the part about windows is especially amusing)"