Below is a link to a good (technical) article on some of the new nefarious things one can do by using HID (Human Interface Device) vectors.
For those of you non-technical (and maybe even a few technical) types, gone are the days where USB and other storage media drives were the “hack” of the day. The wily coyote hacker now realizes that emulating a HID (keyboard, mouse, etc) is far more effective and lethal.
In current computing architectures, HIDs are innately assumed “OK” (aka “safe”). Therefore anything device that can emulate (think Arduino, Teensy, etc) a HID, can bypass many security mechanisms and feed commands straight into the machine. Hacks in this area are on the rise and are predatory.