This is only half the problem, and it is trivial to defeat. What we should really be worried about is malware that acts as a USB keyboard, since that's much har

This is only half the problem, and it is trivial to defeat. What we should really be worried about is malware that acts as a USB keyboard, since that's much harder to protect against. It's also much harder to reliably launch an attack from, but in the case of a targeted attack where the OS is known it wouldn't be too difficult to come up with something that could sneak some nasties in with a low chance of detection.