Bot Cracks CAPTCHA
Posted: Fri Feb 08, 2008 5:57 pm
Spammers' bot cracks Microsoft's CAPTCHA
By Gregg Keizer
February 7, 2008 ([url=\"http://www.computerworld.com/\"]Computerworld[/url]) Spammers are using a bot to sidestep barriers that Microsoft Corp. has erected to keep scammers from creating massive numbers of accounts on its Live Mail service, a security researcher said today.
Dan Hubbard, vice president of security research at Websense, Inc., said the bot was designed to break CAPTCHA (Completely Automated Public Turing Test to Tell Computers and Humans Apart) defenses, the distorted, scrambled character codes that many Web services use to block automated registration of hundreds or thousands of accounts at a time.
The bot, said Hubbard, grabs the CAPTCHA -- which is not plain text but actually an image -- and sends it back to the spammer's server, where the image is somehow "read" and a clear text match is generated. The text is then sent back to Live Mail, where it's plugged into the box where users normally type the CAPTCHA characters.
On average, the bot returns the correct response 30% to 35% of the time and successfully creates an account, Hubbard claimed.
...[i][url=\"http://www.computerworld.com/action/article.do?command=viewArticleBasic&articleId=9061558&source=NLT_VVR&nlid=37\"]read the rest of the article[/url][/i]...
By Gregg Keizer
February 7, 2008 ([url=\"http://www.computerworld.com/\"]Computerworld[/url]) Spammers are using a bot to sidestep barriers that Microsoft Corp. has erected to keep scammers from creating massive numbers of accounts on its Live Mail service, a security researcher said today.
Dan Hubbard, vice president of security research at Websense, Inc., said the bot was designed to break CAPTCHA (Completely Automated Public Turing Test to Tell Computers and Humans Apart) defenses, the distorted, scrambled character codes that many Web services use to block automated registration of hundreds or thousands of accounts at a time.
The bot, said Hubbard, grabs the CAPTCHA -- which is not plain text but actually an image -- and sends it back to the spammer's server, where the image is somehow "read" and a clear text match is generated. The text is then sent back to Live Mail, where it's plugged into the box where users normally type the CAPTCHA characters.
On average, the bot returns the correct response 30% to 35% of the time and successfully creates an account, Hubbard claimed.
...[i][url=\"http://www.computerworld.com/action/article.do?command=viewArticleBasic&articleId=9061558&source=NLT_VVR&nlid=37\"]read the rest of the article[/url][/i]...