Spammers crack Gmail CAPTCHA

Mechanisms put in place by Gmail to prevent bots creating new accounts being opened and used by spammers have been cracked, leading to a surge in spam.

by Helen Leggatt

MessageLabs has confirmed what WebSense reported late last month – that Gmail’s CAPTCHA program has been cracked by spammers. In mid-2007, both Yahoo Mail and Hotmail’s CAPTCHA programs were cracked.

CAPTCHAs, short for "completely automated public Turing test to tell computers and humans apart”, usually consist of a box containing letters and numbers displayed against a confusing background or in a distorted font. For an Internet user to be able to complete various web tasks, such as sign-ins and sending email, they must replicate the box contents. This prevents automated bots from proceeding further.

“Online criminals are going to greater lengths than ever before to reach their targets,” said Mark Sunner, Chief Security Analyst at MessageLabs, in a recent release. “At the same time though, more and more businesses are protecting themselves against potential threats by only allowing employees to access pre-approved websites."

Spam from Gmail reportedly doubled last month from 1.3% of all spam email to 2.6%, according to MessageLabs’ recent research.

Tags: CAPTCHA, Gmail, hackers, online security, online threats, spam, spammers