Security and Usability Challenges of Moving-Object CAPTCHAs: Decoding Codewords in Motion

  title={Security and Usability Challenges of Moving-Object CAPTCHAs: Decoding Codewords in Motion},
  author={Yi Xu and Gerardo Reynaga and Sonia Chiasson and Jan-Michael Frahm and Fabian Monrose and Paul C. van Oorschot},
  booktitle={USENIX Security Symposium},
We explore the robustness and usability of movingimage object recognition (video) captchas, designing and implementing automated attacks based on computer vision techniques. Our approach is suitable for broad classes of moving-image captchas involving rigid objects. We first present an attack that defeats instances of such a captcha (NuCaptcha) representing the state-ofthe-art, involving dynamic text strings called codewords. We then consider design modifications to mitigate the attacks (e.g… CONTINUE READING
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