CircleID

It's one thing to start efficiently registering thousands of email accounts at reputable email providers by automatically breaking their CAPTCHA authentication, and entirely another to build a business model on the top of it next to the opportunity to abuse if for your own malicious purposes. Which is exactly what we have here, an underground service that's selling registered accounts at Gmail, Yahoo, Hotmail and the most popular Russian email providers in the thousands.

Once the inventory of registered accounts drops due to someone's purchase, it continues registering one to two email accounts per second. Gmail, Yahoo and Hotmail's CAPTCHA broken by spammers:

"Breaking Gmail, Yahoo and Hotmail's CAPTCHAs, has been an urban legend for over two years now, with do-it-yourself CAPTCHA breaking services, and proprietary underground tools assisting spammers, phishers and malware authors into registering hundreds of thousands of bogus accounts for spamming and fraudulent purposes. This post intends to make this official, by covering an underground service offering thousands of already registered Gmail, Yahoo and Hotmail accounts for sale, with new ones registered every second clearly indicating the success rate of their CAPTCHA breaking capabilities at these services."

Text based CAPTCHA is so broken, that if major web sites whose services are getting abused don't at least try to slow down the efficient approach of breaking it, we are going to see an entire spamming infrastructure build on the foundation of legitimate email service providers.

This post has been reproduced here from Dancho Danchev's blog.

Written by Dancho Danchev, Independent Security Consultant. Visit the blog maintained by Dancho Danchev here.

Related topics: Malware, Security, Spam