Ever thought about making your own USB Kill? - Page 1
Forum section: electronics / beginners

author: LoveLaika
author_rank: Frequent Contributor
timestamp: July 24, 2021, 04:05:16 am
content: The USB Killer fascinates me as a product. Simply plug it in, and it fries all of your electronics. Fundamentally, the theory behind its operation seems straightforward. It charges up (what I assume to be) supercapacitors, and then discharges them. It seems straightforward in concept, but fundamentally, I have questions about how it works.1. USB's a standard, and you're pumping out current at the data lines. Is it a fixed resistance seen at the data lines, or can it vary by device? Asking cause wouldn't resistance affect current flow from the USB killer? Ohm's law and all that? On that note, how does the damage spread rather than just damaging the USB bus only?2. Thinking about it, the voltage seen at the data lines has to be more than 5 volts, right? If the input resistance is fixed in all devices, I don't see how 5 volts can be a high enough voltage to damage anything. I would assume a boost converter is necessary. But it would have to be small enough to fit the size of a thumb drive.Also curious...I never used one before, but is it possible to salvage anything from the aftermath? I can understand how it kills a motherboard on a computer, but do the effects spread to other peripherals like a hard drive?

author: Nusa
author_rank: Super Contributor
timestamp: July 24, 2021, 04:18:09 am
content: These answers are so trivially googled, you should probably do that. Even wikipedia covers it.

author: Mr. Wizard
author_rank: Unknown
timestamp: July 24, 2021, 05:44:11 am
content: Dave has some videos on circuits like that.EEVblog #469 – Cockcroft-Walton Multiplieris probably the best to start with. Also check out #473.

author: Mr. Wizard
author_rank: Unknown
timestamp: July 24, 2021, 06:47:31 am
content: Also seethis forum thread from 2017, “USB KILLER V3 reverse engineering in progress UPDATED”.

author: David Hess
author_rank: Super Contributor
timestamp: July 24, 2021, 07:18:11 pm
content: Generally the way to go about it is to apply a high voltage high power pulse to cause breakdown of any protective circuits. Some form of capacitive discharge circuit is suitable for this.

author: Terry Bites
author_rank: Super Contributor
timestamp: July 24, 2021, 07:25:45 pm
content: Shove a1/2" chisel in the hole and apply the mallet. Works for me.I'm sure Andy Moir has some ideas!

author: aeberbach
author_rank: Regular Contributor
timestamp: July 26, 2021, 10:19:24 am
content: But not the good chisel, please!

author: Berni
author_rank: Super Contributor
timestamp: July 26, 2021, 10:54:14 am
content: It's simply a high voltage boost converter that takes the 5V supply, boosts it to something like 300V, stores it in capacitors then uses some sort of fast latching switch(diac,SCR, sparkgap.. etc) to dump it all at once into the data lines.More of a question is WHY?!Why would anyone need such a device? There are easier ways of destroying a computer. If you want to wreck a computer you can do it without any tools at all, just kick it really hard or throw it against the floor. It's also too destructive to use as a prank (swapping someones thumb drive with this)

author: Zero999
author_rank: Super Contributor
timestamp: July 26, 2021, 11:09:00 am
content: The only legitimate reason I can think of is for testing. It shouldn't normally kill the entire computer, just the USB controller.

author: magic
author_rank: Super Contributor
timestamp: July 26, 2021, 11:09:33 am
content: I thought about making one many years ago when I had a roommate who kept borrowing my stuff without permissionBut my laziness helped me resist the evil temptation

author: TheAmmoniacal
author_rank: Unknown
timestamp: July 26, 2021, 11:13:56 am
content: These devices to appear to kill the entire machine though, at least most of the time (it turns off and won't turn on again). Don't know why that happens though.

author: magic
author_rank: Super Contributor
timestamp: July 26, 2021, 11:14:30 am
content: Quote from: Zero999 on July 26, 2021, 11:09:00 amAnd your USB controller is what, your southbridge or your SoC?Say hello to a nice little crater in that chip(subject to enough energy being discharged, hopefully that's taken care of in those gadgets)

author: Zero999
author_rank: Super Contributor
timestamp: July 26, 2021, 11:16:02 am
content: Quote from: magic on July 26, 2021, 11:14:30 amIt should be possible to replace it though and you shouldn't lose any data in the hard drive, which is the most important thing.

author: magic
author_rank: Super Contributor
timestamp: July 26, 2021, 11:17:36 am
content: I don't know how well it would couple through the chipset to SATA portsSATA is AC coupled so that could help if ESD protection on the HDD is robust enough.With PATA it could be worse...editAdditional fun anticipated if you use some secure boot TPM full disk encryption rubbish.

author: Zero999
author_rank: Super Contributor
timestamp: July 26, 2021, 11:20:40 am
content: I would have thought that the first piece of silicon the USB hits, would fuse together, forming a short circuit, to the high voltage.

author: magic
author_rank: Super Contributor
timestamp: July 26, 2021, 11:23:37 am
content: It totally depends on available energy. I have seen blown IGBTs with blown drivers and blown PWM controller, through the driversThis puppy doesn't pack 330µF/400V but it may still do some damage.

author: Berni
author_rank: Super Contributor
timestamp: July 26, 2021, 11:24:52 am
content: Quote from: Zero999 on July 26, 2021, 11:09:00 amYeah the problem is that pretty much all motherboards keep the USB controller inside the southbridge/chipset. So once that thing is blown the PC is completely dead. It might survive if the particular motherboard uses a USB hub chip to get more USB ports, in that case it might just kill that collection of USB ports rather than the whole computer.It's also is possible for the voltage to make its way out of the other pins and kill things connected to it(such as the CPU or hard drives), but you probably need to dump pretty large amount of power into there to make that happen. Semiconductors like to fail short, so when the chip dies it mostly shorts things to ground.If you want a easy universal way to kill electronics, use a tazer. No need to even plug it in, just bring it close to some exposed connections and let the arc find its way in. The energy involved there easily exceeds the levels that ESD protection is designed to handle.EDIT: Oh and the reason why it kills the whole southbrige and not just the USB pins is because there is so much energy that the transistors handling the USB lines blow up and melt the area around them, frying important things near them or finding a power rail (those go all over the whole chip) and shorting that to ground.

author: Zero999
author_rank: Super Contributor
timestamp: July 26, 2021, 11:28:09 am
content: A USB protector sounds like a fun project. It doesn't need to survive, just prevent the computer's motherboard and other hardware from being destoryed and be cheap enough.