Gmail CAPTCHA cracked

Posted by   Virus Bulletin on   Feb 26, 2008

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

twitter.png
fb.png
linkedin.png
googleplus.png
reddit.png

 

Latest posts:

Research paper shows it may be possible to distinguish malware traffic using TLS

Researchers at Cisco have published a paper describing how it may be possible to use machine learning to distinguish malware command-and-control traffic using TLS from regular enterprise traffic, and to classify malware families based on their…

Is CVE-2017-0199 the new CVE-2012-0158?

After five years of exploitation in a wide variety of attacks, CVE-2012-0158 may have found a successor in CVE-2017-0199, which is taking the Office exploit scene by storm.

Review: BSides London 2017

Virus Bulletin was a proud sponsor of BSides London 2017 - Martijn Grooten reports on a great event.

VB2017: one of the most international security conferences

It is well known that the problem of cybersecurity is a global one that affects users worldwide - but it's also one that has some unique local flavours. With speakers representing at least 24 countries, VB2017 is one of the most international…

VB2016 paper: Diving into Pinkslipbot's latest campaign

Qakbot or Qbot, is a banking trojan that makes the news every once in a while and was the subject of a VB2016 paper by Intel Security researchers Sanchit Karve, Guilherme Venere and Mark Olea. In it, they provided a detailed analysis of the…