A USB rubber ducky is a USB device that looks like a normal USB thumb drive with the exception that it can be used to send HID commands to a computer just like a keyboard and mouse do. You can purchase a commercial Keystroke Injection Attack Platform or USB rubber ducky from the HakShop or you could make your own DIY USB Rubber Ducky with an Arduino. There are a number of Arduinos that supports HID commands. The Leonardo or the Pro Micro, for instance, are centered around an ATmega32U4. The 32U4 comes with a full-speed USB transceiver interface, allowing the Pro Micro/Leonardo to be programmed to emulate any USB device. In simple terms, you can program the Pro Micro/Leonardo to act just like a mouse, keyboard or other HID-class USB device. There are even libraries available from the Arduino website that allows the 32U4 Arduinos to appear as a native Mouse and/or Keyboard to a connected computer.”