Captcha code is broadly used in different websites to ensure the contents are only accessible by humans rather than bots. The course selection system in my college has also been adopting captcha code in the login page to reduce momentary load of its server. (by slowing down everyone's time to fill in the code and hit log in)
Besides that, the system was kindly designed a "Play Audio" button as well for visually impaired people to "hear" the captcha code. However, it becomes a defect that we can take advantage of the "Play Audio" button function to fill in the captcha code programmatically for us.
Since I have done my last course selection in my college life, I will demonstrate how to fill in the captcha code by exploiting the "Play Audio" button function in below.