Hardware level trojan is relatively hard to develop. I mean, it depends on what do you mean as a trojan. I think it is entirely possible to create a hardware t

Hardware level trojan is relatively hard to develop. I mean, it depends on what do you mean as a trojan. I think it is entirely possible to create a hardware trojan that sends some packets somewhere. It'd make a neat DDoS. :-) Less likely is a classic trojan that gains control over your machine. Do not forget there are many layers between the userland and the hardware (eg, drivers, the network stack etc.). It is a completely different story if evil Bob created both the hardware and the driver...