What is CAPTCHA? CAPTCHA stands for Completely Automated Public Turing test to tell Computers and Humans Apart and it is a system employed by Yahoo, Google, Microsoft and others, designed prevent automated systems that attempt to register web-based email accounts, or to dump spam and guessing passwords on blog comments sections.
What the systems basically do is show users a series of characters that can only be decoded by humans and not by image-recognition software.
Though spammers have managed to come up with a variety of implementations of automated CAPTCHA-cracking software have so far Yahoo's CAPTCHA system has kept its good name due to its high level of security. This is confirmed by a number of websites that sell CAPTCHA cracks and which claim Yahoo's system is almost a virtual Fort Knox when it comes to decoding it.
So it came as a surprise when this week a programmer, apparently from Russia, going under the pseudonym "John Wane" published a code for a decoder system which can reach an accuracy rate around 35 percent according to the alleged security researcher. He stated that Yahoo had been given a notification but so far the company had issued no reply.
The decoder could be used by spammers to, for instance, register Yahoo email accounts for spam purposes or to break through anti-spam features, the researcher said.
Yahoo has announced further development of the system due to the numerous attempts to crack CAPTCHA images.
In 2007 spammers employed a virtual stripper to lure users into helping criminals crack CAPTCHA codes and lately they have been more and more employing methods based on artificial intelligence to successfully deliver their junk to email users.
Unfortunately, there aren’t many ways to efficiently prevent the potential image spam surge and this is more likely to occur as new models employing AI surface. As Forrester analysts put it, the only approach remains the abandonment of the current filtering and a more serious dedicated investigation of the matter.
