National

Twitter hack harmless, but exposes security hole

NEW YORK — A new way to cause mischief quickly spread through short-messaging service Twitter on Tuesday morning before the site could fix the problem, as mysterious tweets of blocked-out text propagated themselves and caused popup windows to open.

Shortly before 9 a.m. Central time, Twitter said on its "safety" feed on the site that the attack had been shut down. It also said it does not think that any user information was compromised, but that the vast majority of the breaches were pranks or promotions.

The hack had been extra-nefarious because the tweets activated without being clicked on — it was enough for Web surfers to move their mouse cursors over them. But it only affected visitors to Twitter.com. Various third-party programs used to send and read tweets, such as Tweetdeck, were unaffected.

The popups could, though didn't necessarily, contain malicious code that could take over poorly protected computers. The White House's official Twitter feed — followed by 1.8 million users — was among those affected, though the offending message was quickly taken down.

Fittingly for Twitter, which limits messages to just 140 characters, the virus may have been among the shortest on record. According to security software maker F-Secure Corp., the shortest virus so far was just 22 characters long.

Twitter said in a blog post it was notified of the security breach at 5:54 a.m. Eastern time. The problem was caused by something called "cross-site scripting." This allowed users to run JavaScript programs on others' computers, turning tweets different colors or causing the pop-up boxes to appear. Some users, Twitter added, took things a step further and included code that got people's accounts to re-tweet the messages without their knowledge.

"It was like a massive snowball fight that got out of control," said Ray Dickenson, chief technology officer at computer security firm SafeCentral.

But while the effects of Tuesday's mischief were very visible and playful, Dickenson said that he was worried because JavaScript can quietly do more malicious things, like sending people to sites that can infect computers.

  Comments