A Survey of Adversarial CAPTCHAs on its History, Classification and Generation. (arXiv:2311.13233v1 [cs.CR])

Completely Automated Public Turing test to tell Computers and Humans Apart,
short for CAPTCHA, is an essential and relatively easy way to defend against
malicious attacks implemented by bots. The security and usability trade-off
limits the use of massive geometric transformations to interfere deep model
recognition and deep models even outperformed humans in complex CAPTCHAs. The
discovery of adversarial examples provides an ideal solution to the security
and usability trade-off by integrating adversarial examples and CAPTCHAs to
generate adversarial CAPTCHAs …

adversarial attacks automated bots captcha captchas classification computers easy history humans malicious public recognition security survey test trade turing turing test usability