CAPTCHA used to be an easy and useful way for Web administrators to authenticate users. Now it’s an easy and useful way for malware authors and spammers to do their dirty work.
CAPTCHA — Completely Automated Public Turing Test to Tell Computers and Humans Apart — was a good idea in its day. You presented users with an obfuscated string of characters and then had them decode and type the string in to get an e-mail account, a social networking account or comment access on an online forum. Not much fuss — though users justifiably complained that the difference between ‘1′ (one) and l (the lower-case letter l) can be hard to see in many fonts — and certainly no muss from a Web administrator’s point of view.
So it was that CAPTCHA went from relatively obscure security measure perfected in 2000 by researchers at Carnegie Mellon University to deployment by most of the major Web e-mail sites and many other Web sites by 2007. Sites such as Yahoo Mail, Google’s Gmail and Microsoft’s Hotmail all used — and, for that matter, continue to use — CAPTCHA to make sure that only human beings, not bots, could get accounts or make postings.
Those days are long gone.
