You arrive at work and find a USB flash drive on your desk; it\u2019s not yours but would you plug it in? Over the years you\u2019ve heard a plethora of security-related reasons not to plug in random USB drives, yet as penetration testers know, curious people who know better still plug in a USB drive found in a parking lot. The scenario about finding a drive on your desk at work is one asked by an engineer who developed a USB drive that could turn your laptop or desktop into toast.An engineer going by the alias of \u201cDark Purple\u201d was allegedly inspired to build USB killer, what is basically a USB bomb, after reading about a guy who plugged in a USB and \u201cburnt half\u201d of his laptop down. Within a week, Dark Purple came up with a plan and ordered the components. While testing the prototype, Dark Purple \u201cburnt down everything I could. Then I developed and ordered printed circuit boards in China and made a combat model.\u201dUSB killer was described by the engineer\u2019s \u201cformer colleague\u201d as being \u201clike an atomic bomb: cool to have, but cannot be applied.\u201d The end product appears relatively boring and \u201charmless.\u201dUSB ports can provide power, such as when you charge your phone or other device via USB. The USB killer at first acts like a normal storage USB while it pulls and stores power until it reaches negative 110 volts; then it sends that surge back into the system. Zap! Not only will that power returned sizzle components and overload circuits, but it will also damage processors. Both AMD and Intel have USB controllers in their CPU die, or core of the computer chip.Thankfully Dark Purple decided against posting step-by-step directions, full schematics and all the app details; however there are a couple of shots showing the soldering.Dark Purple originally posted USB killer on the Russian site Habrahabr; it was later translated into English on Kukuruku.The basic idea of the USB drive is quite simple. When we connect it up to the USB port, an inverting DC\/DC converter runs and charges capacitors to -110V. When the voltage is reached, the DC\/DC is switched off. At the same time, the filed transistor opens. It is used to apply the -110V to signal lines of the USB interface. When the voltage on capacitors increases to -7V, the transistor closes and the DC\/DC starts. The loop runs till everything possible is broken down. Those familiar with the electronics have already guessed why we use negative voltage here. I'll explain to others that negative voltage is easier to commutate, as we need the N-channel field resistor, which, unlike the P-channel one, can have larger current for the same dimensions.Some folks might consider USB killer to be a prank, but \u201cprank\u201d implies it might be funny to some people; only an enemy would consider physical sabotage to be funny. Nevertheless, some commenters on Kukuruku want the full schematics to brick devices and some others want to buy USB killer.The next time you find a USB stick and are curious to know its content, hopefully you\u2019ll stop and remember USB killer.