Exploratory Overview on Breaking CAPTCHAs Using the Theory of the Consolidated Meta-Analytic Approach

This study sought to provide an integrating model of the main contributions of the literature on CAPTCHAs with an impact in this field. With the expansion of internet access, there is an increasing need for a mechanism to protect websites from attacks, although there are situations where it is interesting to be able to automate some activities. This work consisted of identifying the most influential CAPTCHA-related academic works and trends in the field, which could serve as a metric on what approaches to take when developing new studies. Data such as main authors, current lines of research and more prolific research centers are arrived at using the Theory of the Consolidated Meta-analytic Approach. Inputting the keyword “captcha” in the Web of Science database, 539 records were found, from 2001 to 2020. The main classes retrieved are: (a) Captcha in Security Context (31.9%), (b) Usability in Captcha Design (28%), (c) Captcha Recognition by AI (21.8%), (d) Captcha Approaches and Novel Implementation Proposals (18.2%).