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

Re: BusKill: A kill cord for your laptop

#61

Post by geocrasher » Thu, Jan 02, 2020, 3:54 PM UTC

overcast wrote: post #12

thechao wrote: post #5

Earlier quoted context omitted.

Other English speakers I know complain about our orthography: bought, caught, draught, etc. But, yet, here we are with a “word” pronounced “of” and spelled “‘ve”! Now that’s awful orthography!

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

In my household I'm the English nerd, although I have no degree behind it. I'd correct my wife when she wrote "would of" but then I listened closer when she talked: She wasn't saying "would've" she was saying "would of".

That's when I gave up. There are a million other reasons to love my wife, and her proper use of 'would've' wasn't one of them to begin with :)

Re: BusKill: A kill cord for your laptop

#62

Post by Accujack » Thu, Jan 02, 2020, 3:54 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.

Yep. Same effect, really, and in fact this is more likely to be secure because there's a chance that pulling power will damage something or scramble data on disk.

The article's solution is amusing and "cool" but not really secure at all. If you're worried about physical security of devices, don't take them to coffee shops.

Re: BusKill: A kill cord for your laptop

#63

Post by tyingq » Thu, Jan 02, 2020, 4:00 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…

There's sdmem for Linux boxes. It has a -l and -ll option that makes it reasonably fast. So a combination of a duress encrypted volume, then killing only "sensitive processes", then clearing cache via /proc/sys/vm/drop_caches, then sdmem followed by halt might be reasonable protection. Your second point, though, makes sense. It won't always be someone physically grabbing your PC.

Re: BusKill: A kill cord for your laptop

#64

Post by Timpy » Thu, Jan 02, 2020, 4:00 PM UTC

dangus wrote: post #29

This is a really neat project but it’s also not really a solution to anything. First, it doesn’t solve for the scenario of person pointing a gun at you and telling you to access your top secret files for them. That will defeat most forms of security and so if physical access is a concern you probably shouldn’t be logging in at your local coffee shop. Second, a thief who wants your computer for its monetary value isn’…

I agree I think it's a neat project, however you can't say that it's not a solution to anything. The introduction describes a thief snatching and running with your laptop just after you've logged in to your online banking. I think that's a good example of something this solves, even if it's a really narrow use case. Slippery sloping your way to "gun pointed at you" is like saying the lock on my front door doesn't solve for anything because there's a glass window right next to it. BusKill is better for coffee shop thieves than it is top secret gun blazing spies.

Regardless, k_sze posted somewhere else in this discussion xkcd 538 (https://www.xkcd.com/538/) and I have to agree with him.

Re: BusKill: A kill cord for your laptop

#65

Post by ropiwqefjnpoa » Thu, Jan 02, 2020, 4:06 PM UTC

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.

Re: BusKill: A kill cord for your laptop

#66

Post by ShakataGaNai » Thu, Jan 02, 2020, 4:14 PM UTC

jefftk wrote: post #32

dangus wrote: post #29

This is a really neat project but it’s also not really a solution to anything. First, it doesn’t solve for the scenario of person pointing a gun at you and telling you to access your top secret files for them. That will defeat most forms of security and so if physical access is a concern you probably shouldn’t be logging in at your local coffee shop. Second, a thief who wants your computer for its monetary value isn’…

> it’s also not really a solution to anything It's a solution to situations like https://en.wikipedia.org/wiki/Ross_Ulbricht#Silk_Road,_arres... , where the laptop is taken by people who (a) can legally seize it, (b) can legally search it, but (c) probably can't legally compel you to produce passwords. (Not endorsing this usage!)

The author of the article clearly had that or something very similar in mind when he wrote this piece. It reads exactly like that story (I had the same thought as you).

It's a very good solution for people who don't know you have something like this. Clearly if the FBI (or whatever) knew of the USB kill device, they'd take a slightly different snatch and grab approach. However if the adversary doesn't think or doesn't know you have something like this, then it can be used to great effect.

Re: BusKill: A kill cord for your laptop

#67

Post by therealmocker » Thu, Jan 02, 2020, 4:17 PM UTC

jotm wrote: post #39

I guess I'll share in this thread. ---1--- I have a OnePlus 6T with the stock ROM exclusively for my British phone number. On the 25th of December, someone from Canada logged into the GMail account used on that phone, from a OnePlus 3T. The password was one randomly generated in KeePass (all of them are except for useless websites). They managed to change the password to the account, but seemingly nothing else, so th…

Sounds like maybe a SIM swap attack? In addition to password changes I would look into Google's advanced protection program (https://landing.google.com/advancedprotection/) and get U2F or FIDO2 setup on your account.

Re: BusKill: A kill cord for your laptop

#68

Post by RIMR » Thu, Jan 02, 2020, 4:20 PM UTC

dangus wrote: post #29

This is a really neat project but it’s also not really a solution to anything. First, it doesn’t solve for the scenario of person pointing a gun at you and telling you to access your top secret files for them. That will defeat most forms of security and so if physical access is a concern you probably shouldn’t be logging in at your local coffee shop. Second, a thief who wants your computer for its monetary value isn’…

Your first point is moot, because a person could point a gun at you even when you don't have your computer and demand your passwords, or even kidnap you and force you to log on somewhere else. This solution doesn't aim to prevent that kind of thing.

Your second point is moot, because the intent is not to protect the hardware, it is to revoke access to data. A self-destruct protocol is not about preservation of property.

Your third point is moot, because the intent is not to be convenient, the point is to create a dead man's switch.

You're thinking about this from a Consumer/Enterprise standpoint, but that's not what this is for. This would be great for political activists in oppressive countries, as an example.

Re: BusKill: A kill cord for your laptop

#69

Post by nowahe » Thu, Jan 02, 2020, 4:22 PM UTC

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.

Re: BusKill: A kill cord for your laptop

#70

Post by thedanbob » Thu, Jan 02, 2020, 4:22 PM UTC

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.