In Oct. 2015, we wrote about USB Killer — a seemingly innocuous USB stick that fries nearly any device it's inserted into with a bolt of electricity.

Back then, it was a proof of concept, interesting mostly to security researchers and folks who work on USB standards. Now, however, the USB killer has become a gadget anyone can buy.

According to USB Killer's webpage, it's a "testing device" which should be a part of every security auditor and hardware designer's arsenal. The company is also selling the USB Test Shield, a gadget that purportedly lets you safely test a device's resistance to USB Killer's high voltage attack.

The USB Test Shield lets you "test" the USB Killer without destroying anything. Image: USB Kill

The USB Killer's website claims it will destroy 95% of devices it's inserted into. With that kind of destructive capability, one has to wonder how many of these sticks will actually be bought by security experts, and how many by pranksters and malicious individuals looking to destroy someone else's equipment.

The details of who, exactly, is behind the project are somewhat murky. Originally, the USB Killer was demonstrated on video by a Russian hacker known only as Dark Purple. Now, the USB Killer website does not mention who's actually selling the product, but a press release posted on the site indicates Hong Kong might be the company's base.

USB Killer says that 95% of hardware is vulnerable to this attack, but that does not include Apple.

We've reached to the USB Killer's makers, and gotten a surprisingly elaborate answer, though any details about individuals behind the project are still absent. According to a USB Killer spokesperson, it is an "independent Hong-Kong-based company" that specializes in security and audit hardware.

When asked about the potential for abuse, USB Killer responded that they're aware of the risk, but they compare hardware vulnerabilities to software security holes, claiming that raising awareness about these issues will force companies to use better protection for their hardware.

"This vulnerability has been in the wild for years: education of both fronts, consumer and manufacturer, is necessary," the spokesperson told Mashable via a message.

Interestingly, USB Killer says that 95% of hardware is vulnerable to this attack, but that does not include Apple, which is "the only company to [protect its hardware] voluntarily."

So what can individuals do to protect their equipment from such an attack? USB Killer has three possible solutions, the most important being: Don't trust unknown hardware. Alternatively, you can use a USB-protection device, such as this one, or physically cap your USB ports when you're away from the device.

Even though it's a high-voltage device, the USB Killer is touted to be "totally safe." That may be so, but we still wouldn't recommend anyone except security/hardware professionals to try it out.

The USB Killer costs 49.95 euros ($56), and the Test Shield 13.95 euros ($16). The USB Killer website allows for credit card and PayPal payment, and promises "rapid world-wide delivery".