Stiltwalker, Round 2

Stiltwalker is a system we designed to break the audio version of reCAPTCHA. At LayerOne, the original Stiltwalker was released. However reCAPTCHA updated its system to break Stiltwalker in the hours before our talk/release. Prior to these changes, Stiltwalker was able to achieve an accuracy of 99.1%. This talk will describe a narrative of the events that lead to us choosing to break the audio version of reCAPTCHA, the methods we used to break it, the events surrounding our LayerOne talk and reCAPTCHA's response, and most importantly how we have worked around their response to break reCAPTCHA again after their changes since LayerOne.