Imperva says CAPTCHA systems easy to foil

Challenge-response techniques called “CAPTCHAs” designed to keep spambots off Web sites can easily be broken by humans who are paid to type in the responses, according to a new report from security firm Imperva. 

CAPTCHAs, which stands for Completely Automated Public Turing test to tell Computers and Humans Apart, are created by programs and are intended to be difficult for computers to fill out.