If ever you have wanted to kill a computer – any USB device really – for US$49.95 you can buy USB Kill 2.0.
The device is marketed as a tester and works by drawing 5V DC from the USB port into a capacitor and discharging 200V DC back down the data lines – guaranteed to blow any silicon behind it. It is selling like hot chips.
Of course, the makers also have USB Shield that will protect said device, and it only costs US$13.95, and there are discounts for bulk buys.
The issue is that pretty well every USB port on every computing device (except some Apple Macs) has no isolation of data lines and voltage lines.
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Photo booths, copy machines, airline entertainment systems and ticket terminals often have exposed USB ports that are vulnerable to malicious attacks. The USB Kill 2.0 along with USB Shield can be used by testers to check that a device is adequately protected against power surge attacks.
Recent studies have shown that up to 50% of people will cheerfully plug in a USB drive they found on the ground without taking precautions for what kind of data or malware might be on the drive.