Why do websites ask us to fill a CAPTCHA?

I used to get irritated when some sites ask to fill in CAPTCHA? did you also ?

Now read on.....

What is a captcha form?

The word captcha is actually an acronym that stands for ‘completely automated public Turing test to tell computers and humans apart’. Quite a mouthful isn’t it?

Why some sites ask to fill Captcha ?

Simply put, a captcha is used so prevent bots from gaining access to your account.

What this means, in a nutshell, is that a captcha test is a tool that helps to distinguish a human user from a computer user online.

The original form of captcha tests, invented in the late 1990s, took the form of a panel of obscured letters or numbers. The letters were obscured by blurring, stretching or warping. It would then be the internet user’s task to identify these letters and type them into a separate area of the form. If they interpreted the letters correctly, they passed the test

Since the nineties, other forms of captcha tests have emerged.

How do captcha tests work?

Captcha tests can be used to…

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  • Protect the integrity of online polls by stopping hackers using robots to send in repeated false responses.
  • Stop brute force attacks on online accounts in which hackers repeatedly try to log-in using hundreds of different passwords.
  • Prevent hackers from signing up for multiple email accounts that they’ll then go on to use for nefarious purposes.
  • Stop cyber criminals spamming blogs or news content pages with dodgy comments and links to other websites.
  • Prevent ticket touts from using robots to bulk buy tickets for shows and gigs.
  • To make online shopping more secure.

How have organisations suffered as a result of not having a captcha form?

There are a few case studies of organisations and businesses who have suffered as a result of not having captcha forms on their websites. One of the earliest cases dates back to the late nineties when social news website Slashdot published a poll asking visitors to vote for the best computer science graduate course in the USA.
Students from two universities – Carnegie Mellon and MIT – used automated programs to vote repeatedly for their respective schools, and the poll became skewed and useless.
More damagingly, in 2013 big supermarket brand Target suffered from a data breach that affected 70 million people.
Commenting on the breach, Rocket Digital reported: “When Target hired a security company to investigate, one of the leading theories was that the breach was caused by malicious email – specifically a phishing email that went after their customer base.
“They had a vendor portal that did not have a captcha or any kind of human verification in place, so a bot was able to get into the system and start transmitting data back to people who weren’t supposed to have it.


What is a bot ? A bot aka web robot is a software application that runs automated tasks over the Internet. They are mainly programs designed to try crack your password by either Dictionary attack (for weak passwords) or Brute-force attack (for stronger password).



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