Security Flaw in Popular Disk Encryption Technologies

Pieter de Boer pieter at
Sat Feb 23 18:40:56 UTC 2008

Atom Smasher wrote:
> article below. does anyone know how this affects eli/geli?
> from the geli man page: "detach - Detach the given providers, which 
> means remove the devfs entry and clear the keys from memory." does that 
> mean that geli properly wipes keys from RAM when a laptop is turned off?
The attack you're referencing is carried out by cold rebooting a system. 
Simply put: pull power cord, insert power cord. The volumes are never 
detached, as the shutdown sequence is never run.

This attack has to be defended against in hardware; it exploits a 
'feature' of modern day RAM chips, which can not be controlled by 
software. Anything that is in RAM when the attack is carried out, will 
be compromised. As encrypted volumes simply require keys to be in memory 
to be able to use the volumes, the encryption software is vulnerable to 
this attack. I see no reason why GELI/GBDE wouldn't be affected.

A possible counter-measure would be to add wiping features to the RAM 
modules themselves. When power is lost, the memory could wipe itself. 
Still not perfect, but would certainly help.


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