A USB killer is a device built to look like an ordinary flash drive but designed for a very different purpose: rapidly charging internal capacitors from the port's own power supply, then discharging that stored energy back into the port at a much higher voltage than the electronics are designed to handle.
Unlike BadUSB or juice jacking, which target data and software, a USB killer is a hardware attack aimed at permanently damaging the connected computer or device, and its effects usually cannot be undone by any software fix once triggered.
Because a USB killer looks identical to a normal flash drive from the outside, the only real defence is never plugging in unknown or unsolicited USB devices, especially ones received unexpectedly or found lying around. See our USB security guide for wider precautions against USB based threats.
