KeySweeper is a keylogger that sniffs keystrokes sent from any nearby Microsoft keyboard. The FBI has not commented on whether any real-world attacks have been carried out using the tool. The device is relatively inexpensive to make (between $10 and $80 USD) The FBI advises organizations be vigilant about the use and integrity of USB wall chargers. The tool was released in January 2015 by noted hardware hacker and researcher Samy Kamkar, who said he was in the dark as to why the alert was released now.
Source: https://threatpost.com/fbi-mum-on-real-world-keysweeper-attacks/118260/