Researcher Details USB-Based Attack That Circumvents All Known Protective Security Measures
Security research Karsten Nohl of Berlin's SR Labs has revealed a flaw in USB devices that potentially allows hackers to evade all known security measures used by a computer. In a report by Wired, Nohl says his BadUSB exploit is "almost like a magic trick" because "you cannot tell where the virus came from."
http://www.macrumors.com/2014/07/31/usb-security-threat/