USB Killer, yours for $50, lets you easily fry almost every device
USB Killer, yours for $50, lets you easily fry almost every device

          
          
In the video below you can see that a Galaxy Note 7 loses its USB port (so it can't be charged), but otherwise remains functional; likewise, a new iPad Pro freaks out while the stick is plugged in, but seems to regain consciousness afterwards. Curiously, the Pixel is fine when a third-party USB-C converter is used, but using the official Google dongle results in a dead device.

    
    
      One guy fries a ton of stuff with the USB Killer.

          
  

In another video it seems the iPhone 7 Plus suffers a similar fate to the Note 7: the Lightning port is fried, but the rest of the device is okay. You'll also be glad to hear that the iPhone 4 and iPhone 3GS, connected via a 30-pin dongle, both seem to be immune to the USB Killer. All told, the company behind USB Killer says that 95 percent of devices are susceptible to a USB power surge attack.
Without taking a fried device apart it's impossible to say how extensive the damage actually is. When you see the screen go black, and then not return after a reboot attempt, it's likely that the surge travelled to the CPU or some other core component. If the victim device was a desktop PC, you might get away with replacing the motherboard—on a mobile or embedded device, diagnosing and fixing the issue is probably going to be more effort than it's worth.
A better solution, of course, is protecting a system against the USB Killer in the first place, though that isn't an easy task. Electrically, the most simple solution is an opto-isolator: a chip that uses an LED paired with a photodiode to physically isolate one electrical circuit from another. As devices move towards USB-C there's another possible solution: USB authentication.
Neither of those solutions help protect the hundreds of millions—perhaps billions—of devices in the world with unprotected USB ports, though. Cars, airplanes, routers, machines that control industrial centrifuges... in those cases, the only real defence is physically capping ports or educating people to never insert unknown hardware.


          
                  