Captchas are distorted letters and characters that users of an e-mail or social-networking account are required to type to complete certain online forms. They ve become the new front in cybercrime: scams and identity-theft programs that attack e-mails and users of sites such as Facebook and Twitter. For years, these programs have helped to stop or bog down programs aimed at creating fake computer virus protection and bogus accounts that can be used to collect personal information.
Source: https://threatpost.com/cybergangs-use-cheap-labor-break-codes-social-sites-042309/72560/