29 lines
1.8 KiB
Markdown
29 lines
1.8 KiB
Markdown
# Captcha Bypass
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* Do not send the parameter related to the captcha
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* Change from `POST` to `GET` or other HTTP Verbs
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* Change to JSON or from JSON
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* Send the captcha parameter empty
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* Check if the value of the captcha is **in the source code** of the page
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* Check if the value is inside a cookie
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* Try to use an old captcha value
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* Check if you can use the same captcha value several times with the same or different sessionID
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* If the captcha consists on a mathematical operation try to automate the calculation
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* 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
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* Use an OCR (https://github.com/tesseract-ocr/tesseract)
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## Online Services to bypass captchas
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* [Capsolver](https://www.capsolver.com/) 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.
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* [AZcaptcha](https://azcaptcha.com/) is an automated online captcha solver API service which is highly accurate and superbly cheap OCR captcha solver solution.
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## A secure Captcha should have the following features:
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* It cannot be read using automatic Captcha Solver tools
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* It has the necessary high entropy content and cannot be guessed
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* Expiration on both the server and the client side with every wrong entry
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* After each user request, whether successful or unsuccessful, the captcha must be changed and the user should not be allowed to send the request again with the previous captcha.
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* Expires after a short time (about 2 minutes).
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* After successful login, Captcha will expire
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* When a new Captcha code is created, the previous code will expire
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* Using the 2FA or MFA mechanism
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