Testing for Captcha (OWASP-AT-012)
This article is part of the new OWASP Testing Guide v4.
Back to the OWASP Testing Guide v4 ToC: https://www.owasp.org/index.php/OWASP_Testing_Guide_v4_Table_of_Contents Back to the OWASP Testing Guide Project: https://www.owasp.org/index.php/OWASP_Testing_Project
WARNING: Captcha protection is considered to be an ineffective security mechanism!
Most current used Captcha images can be easily cracked in a fully automated way using many commercial or opensource services. Commercial services are usually very cheap and provide a simple API for most programming languages.
It is not recommended to use Captcha protection for security-critical applications, in this case it is more suitable to use SMS text messages or OTP tokens instead.
Example of Google reCAPTCHA cracked in 7 seconds by commercial automated cracking service:
Uploaded: Sun Nov 17 20:03:13 2013
Solved: Sun Nov 17 20:03:23 2013
Text: 270 35524452
CAPTCHA ("Completely Automated Public Turing test to tell Computers and Humans Apart") is a type of challenge-response test used by many web applications to ensure that the response is not generated by a computer.
Description of the Issue
...here: Short Description of the Issue: Topic and Explanation
Black Box testing and example
Testing for Topic X vulnerabilities: