Google has denied that the current version of its reCAPTCHA captcha
service contains vulnerabilities which make it easier for spammers to
guess displayed words using automated scripts.
At the weekend, software developer Jonathan Wilkins published a document
describing a procedure which can be used to increase the hit rate for
automatic recognition of Google captchas to nearly 18 per cent. This
would make the reCAPTCHA procedure as good as cracked, since it would
allow botnets, for example, to create large numbers of email accounts
with reputable providers and use them to send spam.