Hackers hijack Obama's, Britney's Twitter accounts

"This morning we discovered 33 Twitter accounts had been 'hacked,' including prominent Twitter-ers like Rick Sanchez and Barack Obama," said in a post to the company blog. "We immediately locked down the accounts and investigated the issue. Rick, Barack and others are now back in control of their accounts."

Earlier in the day, the hacked accounts had been used to send malicious messages, many of them offensive. CNN correspondent Rick Sanchez's account, for example, tweeted a message claiming that "i am high on crack right now might not be coming to work today," while Fox News' Twitter update reported "Breaking: Bill O Riley [sic] is gay," referring to the network's conservative talk show host.

According to Twitter, the accounts were hijacked using the company's own internal support tools. "These accounts were compromised by an individual who hacked into some of the tools our support team uses to help people do things like edit the e-mail address associated with their Twitter account when they can't remember or get stuck," Stone admitted. "We considered this a very serious breach of security and immediately took the support tools offline. We'll put them back only when they're safe and secure."

Today's admission was only the latest security problem for Twitter. On Saturday, identity thieves on the micro-blogging service that tried to dupe users into divulging their account usernames and passwords.

On Sunday, criminals changed their tactics to use messages about as scam bait, a security expert said Monday. "A lot of users have fallen for the first scam," said , a senior technology consultant at Sophos PLC, describing the Saturday tweets. "Now [the attackers] are changing their modus operandi."