A cross-site scripting flaw that allowed several worms to spread on Twitter has been repaired.

Thomas Claburn, Editor at Large, Enterprise Mobility

September 21, 2010

2 Min Read

Strategic Security Survey: Global Threat, Local Pain

Strategic Security Survey: Global Threat, Local Pain


Strategic Security Survey: Global Threat, Local Pain (click image for larger view and for full photo gallery)

Twitter says that it has fixed a cross-site scripting (XSS) vulnerability that allowed several XSS worms to spread across the site early Tuesday morning.

"We’ve identified and are patching a XSS attack; as always, please message @safety if you have info regarding such an exploit," the company said in a status message posted at 6:25 am PT.

Twenty-five minutes later, Twitter updated the message to say that the fix was complete.

The vulnerability involved improper input cleansing: Twitter failed to deactivate JavaScript code elements in user input. This allowed users to craft malicious tweets that executed when another user allowed his or her mouse arrow to pass over the tweet, sending more infected tweets to the victim's followers.

The discoverer of the vulnerablity was a Japanese developer by the name of Masato Kinugawa, according to The Guardian. Kinugawa's work was then expanded upon by other developers around the world, several of whom created worms that redirect users to adult Web sites.

Graham Cluley, senior technology consultant for Sophos, a U.K.-based security company, notes that one of the victims was Sarah Brown, wife of the former British Prime Minister. After being hit by the worm, Brown's account included a tweet redirecting visitors to a porn site in Japan.

F-Secure, a security company based in Finland, says that while Twitter may have fixed the problem, it expects problems to continue. "It's perfectly possible that there will be more malicious attacks, possibly combining this technique with browser exploits," the company said in a blog post.

A week ago, Twitter introduced "re-engineered" version of its site, promising a better user experience.

About the Author(s)

Thomas Claburn

Editor at Large, Enterprise Mobility

Thomas Claburn has been writing about business and technology since 1996, for publications such as New Architect, PC Computing, InformationWeek, Salon, Wired, and Ziff Davis Smart Business. Before that, he worked in film and television, having earned a not particularly useful master's degree in film production. He wrote the original treatment for 3DO's Killing Time, a short story that appeared in On Spec, and the screenplay for an independent film called The Hanged Man, which he would later direct. He's the author of a science fiction novel, Reflecting Fires, and a sadly neglected blog, Lot 49. His iPhone game, Blocfall, is available through the iTunes App Store. His wife is a talented jazz singer; he does not sing, which is for the best.

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