hacktricks/pentesting-web/captcha-bypass.md

Captcha Bypass

Captcha Bypass

To automate the testing of some functions of the server that allows user input it could be needed to bypass a captcha implementation. Test these things:

• Do not send the parameter related to the captcha.
• Send the captcha parameter empty.
• Check if the value of the captcha is in the source code of the page.
• Check if the value is inside a cookie.
• Check if you can use the same captcha value several times with the same or different sessionID.
• If the captcha consists on a mathematical operation try to automate the calculation.
• If the captcha consists on read characters from an image, check manually or with code how many images are being used and if only a few images are being used, detect them by MD5.
• Use an OCR [https://github.com/tesseract-ocr/tesseract](https://github.com/tesseract-ocr/tesseract).