Twenty per cent success rate sufficient to create thousands of spam accounts.
Gmail
has become the latest free webmail service to have its CAPTCHAs cracked by spammers.
Following the
recent news
of the
Yahoo Mail
and
Windows Live Mail
CAPTCHAs having been cracked, the news of
Gmail
‘s CAPTCHA being surpassed will come as little surprise.
Gmail
, known as
Google Mail
in some countries, is the free webmail service offered by
Google
. Before being able to set up a new
Gmail
account, users are required to solve a CAPTCHA – which was believed to be very hard to crack – thus preventing automated registration of accounts.
However, using the combined forces of two hosts, spammers have managed to crack the
Gmail
CAPTCHAs with a success rate of one in five. As the registration attempts are carried out by bots in a botnet, this is a suffienctly high success rate to allow the attackers to create a large number of free accounts from which to send spam.
Researchers at security company
Websense
, who first discovered the attack, believe that it is being carried out by the same group behind the cracking of
Windows Live Mail
CAPTCHAs earlier this month.
Like both
Windows Live Mail
and
Yahoo Mail
,
Gmail
is a valuable resource for spammers – providing free access to powerful mailing resources, and with its broad popularity and large legitimate user base it provides a domain address that is unlikely to be blocked by spam filters – thus stepping up the challenge for spam- and malware-fighters.
More details are at
Websense
here
and at
The Register
here
.
Posted on 26 February 2008 by
Virus Bulletin
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