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BusKill: A kill cord for your laptop

tech.michaelaltfield.net

161–170 of 272 posts

Re: BusKill: A kill cord for your laptop

#161
post #104

Earlier quoted context omitted.

Ross Ulbricht would like to have a word with you.

they snatched his computer while it he was using it - open and unlocked

I think most MacBook Pros have some accelerometer functions you can access. I wonder if you could create a util to detect if your laptop was picked up and automatically log you out.

Re: BusKill: A kill cord for your laptop

#162

Earlier quoted context omitted.

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…

How long does it take RAM to lose that data though? Most laptops take far more time to remove the ram than a PC and it's soldered down in a lot of cases.

Suprisingly long. I've played around with that a bit a while ago and sometimes up to minutes later you could still recover recognizable bitmaps. But definitely not something you should rely on if you want a bit perfect copy, the first bits start to flip immediately upon power loss, some of them take a lot longer and our brain is pretty good at such reconstruction from noisy data, especially if it knows what it is looking at.

I guess the higher the RAM capacity the shorter it would be because of the decrease in physical cell size.

Re: BusKill: A kill cord for your laptop

#163
post #129

Earlier quoted context omitted.

you'll still have to explain why there is a huge blob of seemingly random data on your hard drive if someone looks close enough.

With whole disk encryption the whole drive is seemingly random data, that's the point.

Last i checked, you don't have to explain sh!t. Besides, I would just tell them i boot from a live cd only to prevent system compromise..

Re: BusKill: A kill cord for your laptop

#164

Earlier quoted context omitted.

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 :)

It's pretty common for law enforcement to quickly freeze RAM when busting hackers. I've definitely read of cases where suspects encryption keys were pulled from RAM using exactly this method.

The killcord would have been useful for Ross Ulbricht (Silk Road) who was busted by the FBI after using his laptop in public - they grabbed it while he had it unlocked and didn't have time to put it in suspend.

Re: BusKill: A kill cord for your laptop

#166
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…

In practice such attacks tend to only be performed in forensics labs after running hardware has been seized.

Re: BusKill: A kill cord for your laptop

#167

Earlier quoted context omitted.

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

It's pretty common for law enforcement to quickly freeze RAM when busting hackers. I've definitely read of cases where suspects encryption keys were pulled from RAM using exactly this method. The killcord would have been useful for Ross Ulbricht (Silk Road) who was busted by the FBI after using his laptop in public - they grabbed it while he had it unlocked and didn't have time to put it in suspend.

> It's pretty common for law enforcement to quickly freeze RAM when busting hackers

I’d really love a citation on this, especially since “quickly” seems to imply that they’d do this out in the field.

Re: BusKill: A kill cord for your laptop

#168
post #87

Earlier quoted context omitted.

It's not pronounced "of", it's more like "ev", exactly like the contraction of words it's made up of. Would have.

To me "would of" and "would've" are pronounced exactly the same. If I said "would ev" that would sound weird. It would sound very similar to "whatev": https://www.urbandictionary.com/define.php?term=whatev

Well, nothing else in english is pronounced like it is written, so I don't think this is a good reason to misspell things.

Re: BusKill: A kill cord for your laptop

#169

Earlier quoted context omitted.

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 :)

A secure location is an ICBMable location. (Not that anyone realistically has this problem, but “so safe that Bin Laden would still be alive” feels like the right level of overengineering when it comes to OPSEC.)

Re: BusKill: A kill cord for your laptop

#170
It appears breakaway mag USB-A connectors are pretty cheap: https://www.amazon.com/Griffin-Breaksafe-Magnetic-Breakaway-...

From tidbits in this thread, it sounds like a Veracrypt hidden volume with a distress passphrase, plus a fairly simple dead-man script wouldn't be hard to set up. Something like: kill sensitive processes, drop caches, wipe memory, then panic the kernel.

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