  Firewire cables      • read arbitrary RAM contents from the
victim's system,   • overwrite arbitrary RAM contents with
whatever you want,    Papers, Attacks, and Tools   Maximilian
Dornseif et. al.    Adam Boileau    Peter Panholzer   David R.
Piegdon         Mitigation: Linux       $ rmmod ohci1394   $
modprobe ohci1394 phys_dma=0      # Prevent automatic loading of
the ohci1394 module.   blacklist ohci1394   # Prevent manual
loading of the ohci1394 module.   install ohci1394 false
options ohci1394 phys_dma=0   Mitigation: Mac OS X
Mitigation: Windows        Further Resources       Comment
viewing options   use nvmram security-mode to disable firewire
DMA on OS X  On OS X as noted here:  Setting security-mode to
anything other than 'none' puts the firewire controller into
secure mode, disabling Firewire DMA. This is effective even
without setting a firmware password: nvram security-mode=NONE
Or just power down, right?  Just to be clear, this attack is
valid if your computer is asleep or powered up