Message-ID: <4A7D91A8.5080902@gmx.de>
Date: Sat, 08 Aug 2009 16:54:32 +0200
From: Marc Ballarin <Ballarin.Marc@gmx.de>
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References: <20090808132614.GA29656@fancy-poultry.org>
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Subject: Re: [dm-crypt] LUKS/dm-crypt vulnerable?
To: dm-crypt@saout.de

Hi,
of course, this also affects dm-crypt - or any other encryption scheme 
for that matter.

You need an unbroken chain of trust to achieve security. You must be 
able to trust your hardware/firmware, your BIOS, the code in your MBR, 
your boot loader, your kernel, your drivers, your system libraries, your 
shell, your cryptsetup executable and so on.

If an attacker manages to replace or manipulate at least one piece of 
that chain, he has broken your security.
Here is an example of a keylogger implemented in keyboard firmware: 
http://www.blackhat.com/presentations/bh-usa-09/CHEN/BHUSA09-Chen-RevAppleFirm-SLIDES.pdf 
(Yes, even keyboards might come with programmable flash nowadays ;-)

However, this is nothing new. If you assume that an attacker is 
determined and able to get physical access to your computer - especially 
without your knowledge - securing your system gets much, much harder.

In this case you need a method to verify the integrity of every compnent 
of your system. The best bet would probably be something like TPM. This 
should cover at least the BIOS and the rest of the software but 
manipulated firmware might still slip through.

Marc