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Cold Reboot Attacks on Disk Encryption
Cold Reboot Attacks on Disk Encryption
Posted Feb 21, 2008 16:38 UTC (Thu) by rvfh (subscriber, #31018)In reply to: Cold Reboot Attacks on Disk Encryption by flewellyn
Parent article: Cold Reboot Attacks on Disk Encryption
I think what you really want to do is wipe at shut down, and I am sure this is dead easy to program into the Linux kernel ! Don't know how fast that is, but start-up memory test being a few seconds, I'd guess the same time or less to wipe a few GB of memory.
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Cold Reboot Attacks on Disk Encryption
Posted Feb 21, 2008 16:46 UTC (Thu) by Los__D (subscriber, #15263) [Link]
And the attacker just pulling the plug, when the s/he obviously has access to the machine is avoid how?
Cold Reboot Attacks on Disk Encryption
Posted Feb 21, 2008 17:35 UTC (Thu) by JamesErik (subscriber, #17417) [Link]
Surely there's enough capacitance in modern motherboards to provide a few milliseconds of CPU time when power is lost such that the kernel could detect the start of a power loss event and can tell the crypto-disk driver to erase its encryption keys? Or not?
Cold Reboot Attacks on Disk Encryption
Posted Feb 21, 2008 17:55 UTC (Thu) by cventers (subscriber, #31465) [Link]
Perhaps, but I suspect that even that would not be enough. Imagine an FBI raid... they bring along their PC, plug it in and get it ready, open your case, blast off your RAM with the duster, and then perhaps pull the DIMMS out of your running system and slap them into theirs. No power loss event, and no interrupt telling the kernel "Quick! Someone is unplugging the DIMM, write zeros to it before they can finish!" I'm glad this research was done, but reading something like this is unsettling for encryption in general. I think what we need is some kind of 'secure DIMM' that uses capacitance and sets all its bits to 0 or 1 the moment it loses power. Or perhaps it could somehow drain all rows and columns to a big load? (Disclaimer: I'm not an EE)
Cold Reboot Attacks on Disk Encryption
Posted Feb 21, 2008 17:59 UTC (Thu) by tcoppi (subscriber, #44423) [Link]
I think using superglue/epoxy on the chips combined with power-on memory checking and disabling of external boot devices(such as network or usb booting) should be able to mitigate this attack well enough, at least for all but the most paranoid of us.
Cold Reboot Attacks on Disk Encryption
Posted Feb 21, 2008 18:43 UTC (Thu) by zlynx (subscriber, #2285) [Link]
Use a case-open sensor or five to trigger thermite "heat sinks" (heh) mounted on your hard disks and RAM. Physical destruction is the only way to be sure.
Cold Reboot Attacks on Disk Encryption
Posted Feb 21, 2008 19:28 UTC (Thu) by cventers (subscriber, #31465) [Link]
As long as we're playing that game, what if they splice open the power cable and attach their own source so that they can untether it from your outlet, then take it back to their lab where they can use ultrasound to find the case sensors, then cut around them? :p Seriously though, there is often a cost factor in making security decisions, and I would like to think that so-called "secure DIMMs" that are designed to quickly empty themselves upon power loss become prevalent. Extraction could still be possible by carefully applying the right power to the right pins while removing the chips, but at least it wouldn't be as easy as the attack described in this paper appears to be.
Cold Reboot Attacks on Disk Encryption
Posted Feb 21, 2008 22:36 UTC (Thu) by endecotp (guest, #36428) [Link]
> what if they splice open the power cable and attach their > own source so that they can untether it from your outlet, > then take it back to their lab I think you were joking, but that's actually exactly what they do: http://www.engadget.com/2007/11/06/wiebetech-hotplug-lets...
Cold Reboot Attacks on Disk Encryption
Posted Feb 23, 2008 22:42 UTC (Sat) by macc (subscriber, #510) [Link]
GPS? tilt sensor or one of these little gyro thingies used for model helicopters? Then moving the box would shut the OS down? G! MACC
Cold Reboot Attacks on Disk Encryption
Posted Feb 26, 2008 5:52 UTC (Tue) by njs (subscriber, #40338) [Link]
Naw, don't shut down. Presumably the real solution is to every n minutes throw away crypto keys and at the next attempt to access the encrypted data, require the passphrase be re-entered. (We assume that attackers can't or won't breach the case to suck things out in less than n minutes.) Then if you want to get fancy, you can also add accelerometers to the list of things that trigger the crypto keys being flushed. Nagging the user on a timer is somewhat annoying, of course, but should be practical if one really has secret data (and if you segregate out the actually secret stuff from the everyday stuff). It might even be a feature to bug the user occasionally while they have secret data open, to remind them of this fact -- sort of a modern equivalent to root's "#" prompt.
Cold Reboot Attacks on Disk Encryption
Posted Feb 25, 2008 13:11 UTC (Mon) by forthy (guest, #1525) [Link]
"Intrusion detection" is the key here. Add an acceleration sensor to your case, and make sure to set the thresholds so that any small case movement causes the system to erase its memory and shut down. Optimally screw the case to the wall so that you have to open it to move it, anyway, and no accidental kick with your foot will trigger the sensor. And remember to put trip wires around your door - as typical geek, you are supposed to be lonely (you know all your friends only by their IRC nicks, and all women you know have the jpeg surname ;-), so the likelyhood that someone else trips over your trip wires is extremely small ;-).
Cold Reboot Attacks on Disk Encryption
Posted Feb 21, 2008 17:58 UTC (Thu) by alecs1 (guest, #46699) [Link]
Interesting question. Some folks told me once that power failed gradualy (a few until seconds until incandescent bulbs went out completely) and they saw the Windows shutdown screen, so probably the OS tried to go down in an emercency. I never knew if to believe them or not.