Three-Way Dissection of a Game-CAPTCHA: Automated Attacks, Relay Attacks, and Usability.
Manar MohamedNiharika SachdevaMichael GeorgescuSong GaoNitesh SaxenaChengcui ZhangPonnurangam KumaraguruPaul C. van OorschotWei-bang ChenPublished in: CoRR (2013)