The 'USB Killer' Won't Fry Your Computer. Probably.

​Imagine a USB thumb drive that looks just like any other one, but is actually rigged to discharge a destructive amount of electricity to your enemies' computers, sort of like a lightning strike, burning the machine's inner components. That's the stuff of spy lore, or maybe just teenagers with a penchant for awful pranks.

Well, that device could be a reality—at least, if you believe a blog pos​t written last month by a Russian engineer who goes by the pseudonym Dark Purple, who dubbed his creation the "USB Killer."

That blog post was then translated by a collaborative tech blog called Kukuru​k Hub a few days ago, and since then it's gone viral, garnering widespread coverage from countless English-language websites.

A blogger at The Huffington Post, for example, descr​ibed it as a "trap to destroy your laptop." The Daily Mail w​rote that the device "FRIES" laptops.

Dark Purple's post, however, is kinda vague on what the device can actually achieve, and it's unclear he even tested it. (I could not reach Dark Purple, whoever that is, for comment.)

Regardless, electrical engineering experts are skeptical.

"I doubt anything will 'burn' visibly," David Vallancourt, a senior lecturer in circuits and systems at the Department of Electrical Engineering at Columbia University, told me in an email. "His device might indeed damage the USB port so it won't operate anymore. Maybe in a poorly designed piece of equipment it might take out a few other things inside too, but 'half the laptop burned down'? Unlikely."

In theory, the USB Killer is designedto use its capacitors, which replace its normal hardware, to suck up and store energy from the computers' USB port. And, once it has collected enough energy, it drives it back to the system, discharging energy rapidly as many times as it can, until it damages the computer.

This is certainly possible in theory, according to both Vallancourt and Ken Mai, a senior systems scientist at Carnegie Mellon University's Electrical and Computer Engineering department.

But with the way computers are designed, its damage could be limited.​

The USB Killer damaging a USB port would likely stop the flow of electricity and energy into the USB Killer, "and therefore end its ability to harm other components," Mai told me.

Moreover, depending on the specific design of the targeted computer, according to Mai, the damage could spread to the motherboard's "southbridge" chipset, which normally handles the peripherals but is usually not connected to the CPU. So it's only "a remote possibility" that this malicious USB drive could damage the CPU or the hard drive.

So much for "killer."

"The takeaway should be that this USB attack is not something to be worried about, but don't try it at home," Vallancourt said, adding that an easy way to test this would be to wire a wall outlet to a computer's USB port "and see what happens." (Vallancourt advised against actually trying that with your own computer.)

No matter if this device is real, you should still be very careful what you plug into your computer's USB ports. USB drives are well-known to carry viruses and malware, so much so that security experts recommend never using USB drives that you don't trust.

"Plugging unknown hardware into your PC is just a really bad idea," Mai told me. "It's equivalent to finding a sandwich in the street and eating it. Or finding a jug labeled 'gas' in the street and pouring it into your car."

So folks, don't trust random USB drives. They might not fry or kill your computer, but they might infect it with spyware designed to steal your personal data, which could actually be worse than a damaged USB port.