This is a recent story that A guy stole a USB drive from a subway. A guy plugged that USB Drive into his computer and instead of any virus attack, it completely blast his computer.
This above story was told to a Russian researcher, nicknamed Dark Purple, who found the concept very interesting and developed his own computer-frying USB Killer pendrive.
He is working with electronic manufacturing company from where he ordered some circuit boards from China for creating his own USB killer stick.
To get around or break through these protections, [Dark Purple]’s design uses an inverting DC-DC converter. The converter takes power from the USB port to charge a capacitor bank up to -110VDC. After the caps are charged, the converter shuts down and a transistor shunts the capacitor voltage to the data pins of the port. Once the caps are discharged, the supply fires back up and the cycle repeats until the computer is fried (typically as long as bus voltage is present). The combination of high voltage and high current is enough to defeat the small TVS diodes on the bus lines and successfully fry some sensitive components—and often the CPU. USB is typically integrated with the CPU in most modern laptops, which makes this attack very effective.
Therefore, next time when you find an unknown USB flash drive, just beware before inserting it into your laptop. Because it can blast your computer.