BusKill: A kill cord for your laptop • Hacker News Board

Re: BusKill: A kill cord for your laptop

#71

Post by [deleted] » Thu, Jan 02, 2020, 4:23 PM UTC

ianbooker wrote: post #60

dangus wrote: post #48

Earlier quoted context omitted.

If they don’t have due process laws they can throw you in jail until you produce the decryption password, and if they turn on the computer and it’s wiped they’ll throw away the key. If there is no due process, all bets are off and your best defense is to be uninteresting to authorities.

Things are not always black and / or white. The rule of law, in reality, is rather a continuous variable then a binary one. And even if: A kill switch can simply hide / erase some things and present some weak evidence..

[deleted]

Re: BusKill: A kill cord for your laptop

#72

Post by ropiwqefjnpoa » Thu, Jan 02, 2020, 4:26 PM UTC

nowahe wrote: post #69

ropiwqefjnpoa wrote: post #65

The article keeps saying "self-destruct" but that's not what happens. But if your hard drive is encrypted, this is a pretty good solution for most people. Maybe if you can get BusKill to activate a mini thermite explosive under your hard drive.

I remember watching a Defcon conference where they tested different methods for destroying a hard drive in place. And they found that thermite actually doesn't damage the platters (well at least not enough for data to be unrecoverable). Hard drive platters are surprisingly heat/chemical resistant. I think they found that the best method was to physically destroy the platters.

Did they test SSDs?

Re: BusKill: A kill cord for your laptop

#73

Post by jbarberu » Thu, Jan 02, 2020, 4:30 PM UTC

wongarsu wrote: post #35

k_sze wrote: post #16

Earlier quoted context omitted.

If you are doing proper OpSec, you would have whole disk encryption anyway, in which case destroying the computer is largely unnecessary, I think. That said, the caveat of XKCD 538 ( https://www.xkcd.com/538/ ) still applies.

In theory an adversary could deep-freeze the computer the moment the kill cord activates. Sufficiently cold RAM doesn't loose data immediately when it loses power, allowing the adversary to make a copy and read the decryption keys from RAM. Though if this is part of your threat model you should be much more concerned about a thousand more mundane problems, like adversaries reconstructing keystrokes from keyboard vibr…

If your attack vector is adversaries ready to deep freeze your laptop, perhaps you should do your computing in a more secure location :)

Re: BusKill: A kill cord for your laptop

#74

Post by ropiwqefjnpoa » Thu, Jan 02, 2020, 4:31 PM UTC

thedanbob wrote: post #70

ropiwqefjnpoa wrote: post #65

The article keeps saying "self-destruct" but that's not what happens. But if your hard drive is encrypted, this is a pretty good solution for most people. Maybe if you can get BusKill to activate a mini thermite explosive under your hard drive.

Making it self-destruct is the easy part, just change "DISPLAY=:0 xscreensaver-command -lock" to "sudo rm -rf /" or whatever you like. It's understandable that the author didn't want to put a destructive command in his example configuration.

A drive wipe might take too long though, especially if they grab the laptop and shut if off. After a simple shutdown or lock, disk encryption really is the primary protection here.

Re: BusKill: A kill cord for your laptop

#75

Post by crankylinuxuser » Thu, Jan 02, 2020, 4:35 PM UTC

It reminds me of USBkill https://github.com/hephaest0s/usbkill

Its primary use is to thwart machine fuzzing and debugging using USB devices. The moment there's a change in USB state, down the machine goes.

Re: BusKill: A kill cord for your laptop

#76

Post by ShakataGaNai » Thu, Jan 02, 2020, 4:35 PM UTC

savingGrace wrote: post #53

Another solution would be to just remove the battery and plug the laptop in. While this removes the portability, it is still an alternative solution.

Maybe a decade or so ago this would be a good answer. But unless you're one of those ThinkPad people who are still pulling for the X220 to make a come back.... A majority of modern laptops don't have user removable batteries.

Yes, they could still be removed in some cases, but its often not for the feint of heart and not something many people would want to undertake.

Re: BusKill: A kill cord for your laptop

#77

Post by jonnycomputer » Thu, Jan 02, 2020, 4:59 PM UTC

There was a story not long ago about an old man who rigged up his front door to trigger a gun of some sort on unexpected entry, and ended up getting killed by it.

This really just sounds like a way to inadvertently brick your computer 999 times out of 1000. Seems like something to secure it to your person would be mostly adequate.

Re: BusKill: A kill cord for your laptop

#78

Post by Buge » Thu, Jan 02, 2020, 5:01 PM UTC

jonnycomputer wrote: post #77

There was a story not long ago about an old man who rigged up his front door to trigger a gun of some sort on unexpected entry, and ended up getting killed by it. This really just sounds like a way to inadvertently brick your computer 999 times out of 1000. Seems like something to secure it to your person would be mostly adequate.

This specific implementation doesn't brick it. It just locks the screen (or you could make it shutdown).

Re: BusKill: A kill cord for your laptop

#79

Post by Buge » Thu, Jan 02, 2020, 5:03 PM UTC

wongarsu wrote: post #35

k_sze wrote: post #16

Earlier quoted context omitted.

If you are doing proper OpSec, you would have whole disk encryption anyway, in which case destroying the computer is largely unnecessary, I think. That said, the caveat of XKCD 538 ( https://www.xkcd.com/538/ ) still applies.

In theory an adversary could deep-freeze the computer the moment the kill cord activates. Sufficiently cold RAM doesn't loose data immediately when it loses power, allowing the adversary to make a copy and read the decryption keys from RAM. Though if this is part of your threat model you should be much more concerned about a thousand more mundane problems, like adversaries reconstructing keystrokes from keyboard vibr…

I've always heard that cold boot attacks like that require the ram to be frozen before the computer turns off (or the ram is removed).

Re: BusKill: A kill cord for your laptop

#80

Post by dwyerm » Thu, Jan 02, 2020, 5:05 PM UTC

nowahe wrote: post #69

ropiwqefjnpoa wrote: post #65

The article keeps saying "self-destruct" but that's not what happens. But if your hard drive is encrypted, this is a pretty good solution for most people. Maybe if you can get BusKill to activate a mini thermite explosive under your hard drive.

I remember watching a Defcon conference where they tested different methods for destroying a hard drive in place. And they found that thermite actually doesn't damage the platters (well at least not enough for data to be unrecoverable). Hard drive platters are surprisingly heat/chemical resistant. I think they found that the best method was to physically destroy the platters.

Highly recommended by me, too: Zoz at DefCon 23, entitled "And That's How I Lost My Other Eye...Explorations in Data Destruction"

https://www.youtube.com/watch?v=-bpX8YvNg6Y