Twitter is Latest Victim in Series of Attacks

Today's denial of service (DOS) attack on Twitter is the latest in a series of electronic attacks this year on major Internet properties, which have targeted large web hosts and domain registrars, and more recently have expanded to prominent social media sites.

The attacks knocked Twitter offline for most of the morning, with both Netcraft and Pingdom reporting about three hours of downtime. Twitter co-founder Biz Stone confirmed that the outage was caused by a denial of service attack, which affected both the Twitter web site and the services that access Twitter data via API calls, according to the Twitter status page.

UPDATE: Facebook is now confirming that its performance problems this morning were caused by a similar attack. "Earlier this morning, Facebook encountered network issues related to an apparent distributed denial of service attack, that resulted in degraded service for some users,” the company said in a statement. “No user data was at risk and we have restored full access to the site for most users."

UPDATE 2: Sources at Facebook tell CNet's Elinor Mills that today's attacks  targeted the profile of a single user on multiple social media sites, including Twitter, Facebook, LiveJournal, Blogger and YouTube.  "It was a simultaneous attack across a number of properties targeting him to keep his voice from being heard," said Max Kelly, chief security officer at Facebook.

While Twitter has a history of uptime challenges, other recent attacks have disrupted service at some of the largest hosting providers, including companies who are experienced in defending against these type of attacks. Here's a review of the major attacks seen in 2009:

Denial of service attacks use large networks of computers (often compromised desktop computers) to generate traffic that overwhelms a web site or network. These attacks have become more powerful in recent years as these "botnets" have grown in size.

Obviously, there's no way to know whether any of these attacks are connected. But a worrisome common thread is that these were all large-scale attacks that disrupted service for large providers.