Twitter Inc. has launched a comprehensive review of the defenses in its popular social network and microblogging service after hackers last week hijacked the accounts of several high-profile users.

In interviews last week, analysts said they were surprised that sites like Twitter, potentially hot targets for hackers and phishers, had long avoided such major attacks, and thus strong scrutiny by its corporate users.

Since last week's widely-publicized hack of the site, analysts said they are closely watching how Twitter and especially its corporate customers respond to the security breach.

"Certainly, with all the coverage Twitter has had about this, it will bring security to [Twitter's] attention," said Caroline Dangson, an analyst at IDC in Framingham, Mass.

"It reminds us that we're dealing with a medium that is less secure and [that] we need to be more conscious of what we're putting out there and not take it for granted like we have," she added.

San Francisco-based Twitter confirmed last Monday that hackers had broken into the accounts of more than 30 celebrities and organizations, including President-elect Barack Obama, Britney Spears, and the Fox News and CNN cable television networks.

The company said tools used by its support team were illegally accessed and used to send malicious messages, many of them offensive, to the compromised accounts.

The network was breached just two days after identity thieves launched a Twitter phishing scam that tried to dupe users of the microblogging service into divulging their usernames and passwords.

In a blog post on the company's web site, Twitter co-founder Biz Stone said he considers last week's compromise to be "a very serious breach of security."

In an e-mail to Computerworld, Stone added, "We're doing a full security review on all access points to Twitter." The first steps will be to "strengthen the security surrounding sign-in" and to further restrict access to the company's own support tools, he said.

Ken van Wyk, principal consultant at KRvW Associates LLC in Alexandria, Va., said that while individual users are unlikely to change microblogging habits due to the breach, corporate IT managers should move quickly to evaluate how such incidents could affect their firms.

"We're seeing [Twitter] used more and more for communications between managers and employees to keep everyone informed about what's going on," he said. "I suspect that a few of those folks might have a knee-jerk reaction to something like this and stop using it."

He added that the breach could inspire some IT organizations to develop applications that provide Twitter-like capabilities for in-house use.

Dangson agreed that companies should evaluate potential alternatives to Twitter or complementary, more secure tools to use with the service.

"We're not going to see a lot of people stop using [Twitter] because of this, but they might consider other forms of communication -- more closed networks for certain information they're trying to share," she said. "I think people will be more cautious but they won't stop using Twitter."

Stone said that he expects that corporate users will see Twitter's "reaction and immediate behavior" following the breach as "a signal that we're serious about security and supporting commercial use."

As for home users, vanWyk said, "I don't' think people will say, 'Hey, now this place is corrupt.' I suspect [Twitter] will come away unscathed."

However, he added, "I think it would be good for companies to suffer a little bit when there's a major security breach. If they come through unscathed, where is the lesson? Where's the push to improve security?"

Gregg Keizer contributed to this article.