We (Netragard) recently completed an engagement for a client with a rather restricted scope. The scope included a single IP address bound to a firewall that offered no services what so ever. It also excluded the use of social attack vectors based on social networks, telephone, or email and disallowed any physical access to the campus and surrounding areas. With all of these limitations in place, we were tasked with penetrating into the network from the perspective of a remote threat, and succeeded.

The first method of attack that people might think of when faced with a challenge like this is the use of the traditional autorun malware on a USB stick. Just mail a bunch of sticks to different people within the target company and wait for someone to plug it in; when they do its game over, they’re infected. That trick worked great back in the day but not so much any more. The first issue is that most people are well aware of the USB stick threat due to the many published articles about the subject. The second is that more and more companies are pushing out group policies that disable the autorun feature in Windows systems. Those two things don’t eliminate the USB stick threat, but they certainly have a significant impact on its level of success and we wanted something more reliable.

Enter PRION, the evil HID.


A prion is an infectious agent composed of a protein in a misfolded form. In our case the prion isn’t composed of proteins but instead is composed of electronics which include a teensy microcontroller, a micro USB hub (small one from RadioShack), a mini USB cable (we […]