hacktricks/pentesting-web/captcha-bypass.md

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Captcha Bypass

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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. Therefore, try to test for these things:

  • Do not send the parameter related to the captcha.
    • Change from POST to GET or other HTTP Verbs
    • Change to JSON or from JSON
  • 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.
  • Try to use an old captcha value
  • 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 of 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).

Online Services to bypass captchas

Capsolver

Capsolvers automatic captcha solver offers the most affordable and quick captcha-solving solution. You may rapidly combine it with your program using its simple integration option to achieve the best results in a matter of seconds.

With a success rate of 99.15%, Capsolver can answer more than 10M captchas every minute. This implies that your automation or scrape will have a 99.99% uptime. You may buy a captcha package if you have a large budget.

At the lowest price on the market, you may receive a variety of solutions, including reCAPTCHA V2, reCAPTCHA V3, hCaptcha, hCaptcha Click, reCaptcha click, Funcaptcha Click, FunCaptcha, datadome captcha, aws captcha, picture-to-text, binance / coinmarketcap captcha, geetest v3 / v3, and more. With this service, 0.1s is the slowest speed ever measured.

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