\subsection{CAPTCHA farms}
CAPTCHA farms are run using cheap labor available in third-world countries. When
an attacker seeks the services of a CAPTCHA farm, they are provided access to an
web API to forward CAPTCHA challenges. A labourer working in the farm solves the
CAPTCHA and the API responds with the solution. The whole process takes less
then a minute to complete and costs only a fraction of what premium services
like reCAPTCHA charge.

Overall, this attack is very feasible and cheap and is frequently used to bypass
traditional CAPTCHA systems.

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