In this blogpost, we present Hydradancer, a new board for Facedancer based on HydraUSB3 allowing faster USB peripherals emulation.

We recently begun to search bugs in USB host stacks using one of our tool based on the Facedancer. This article first presents our fuzzing approach followed by a practical example of a bug in Windows 8.1 x64 full-updated. The goal of this article is not to redefine state-of-the-art USB fuzzing, nor to give a full description of our fuzzing architecture, but rather to narrate a scenario which starts from fuzzing and ends up with a bug report.