WHMCS is an automation platform that simplifies and automates all aspects of operating an online web hosting and domain registrar business. It is widely used for different purposes.
WHMCS provides at least two types of captchas, one is the traditional captcha with 5 characters and a simple background (but no noise in this case). Also there is reCaptcha provided for better security and you should always choose this option over the traditional one.
Below, you can see a sample of the traditional captcha provided in one of the latest versions of whmcs.
As you can see it is a pretty simple one. All I needed to do was to gather an appropriate dataset, create the model and start training.
The captcha is produced using a php script named as verifyimage.php. All I needed to do was to find this on the internet and run it a few thousand times. So, that was what I did (verifyimage.php).
You can also find the script I used to create my datasets under util/captcha.php.
I used CaptchaCracker for training which is really straightforward and easy to use. In addition, you can see the notebook I used to train my model in whmcs_captcha.ipynb. Moreover, I used Google Colab for my computations.
Finally, the accuracy of the model was 99% which was anticipated because of the simplicity of the captchas.
I also created a tiny webserver using fastAPI for which you can find the code in http-server. You have to install the dependencies mentioned in the requirements.txt file before running the webserver. Also make sure you have tensorflow installed. I recommend using tensorflow on docker if you don't already have it installed.
To start the server you should just run python main.py.