We carry out a systematic study of existing visual CAPTCHAs based on distorted characters that are augmented with anti-segmentation techniques. Applying a systematic evaluation methodology to 15 current CAPTCHA schemes from popular web sites, we find that 13 are vulnerable to automated attacks. Based on this evaluation, we identify a series of recommendations for CAPTCHA designers and attackers, and possible future directions for producing more reliable human/computer distinguishers.
You might also like reading

captcha 2011

The Failure of Noise-Based Non-Continuous Audio Captchas

captcha 2014

Easy Does It: More Usable CAPTCHAs

security 2014

Meaning matters: Why Google switched to numeric captchas

security 2012

How we broke the NuCaptcha video scheme and what we propose to fix it

Comments are loading
About me
Lead Google's anti-abuse research. Develop new ways to protect users and disrupt bad guys. Make Chrome safer and faster. Help keeping G+ and Gmail clean. Wear berets. Do magic tricks.