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Twitter and Others Attacked by DDoS, But What Is It?

August 06, 2009 06:30 PM
by Liz Colville
Twitter was faced with a server shutdown the morning of Aug. 6 following a Distributed Denial of Service attack, or DDoS.

Twitter Outage and Problems at Facebook, LiveJournal

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The Distributed Denial of Service that Twitter faced was believed to be "a deliberate and simultaneous attempt to take down some of the web’s most popular social media sites," Adam Ostrow wrote for the social media blog Mashable.

Along with Twitter, Facebook also "encountered network issues related to an apparent distributed denial-of-service attack, that resulted in degraded service for some users," a company spokesperson was quoted as saying by CNET.

Previous DDoS attacks have targeted sites including Yahoo, eBay and Amazon.

Some have lasted much longer than the two-plus hours Twitter spent in the dark this morning. In April 2009, Register.com, which hosts e-mail and Web domains, was the victim of a DDoS attack that "disrupt[ed] service for thousands of customers," The Washington Post blog Security Fix reported. Service was not fully restored for about 48 hours, according to the Post, which angered some customers and caused at least one, John Ketchpaw, co-owner of the site panopto.com, to switch to a different domain host altogether.

Despite the fact that the Twitter outage was relatively brief, there was a veritable "outcry" over users' inability to access the site, notes PC World's Tony Bradley. This "is indicative of just how far the social network has come in terms of overall reliability," he says, "and also illustrates just how many people depend on Twitter as a source of information, or entertainment, or communication."

But Bradley adds that Twitter must thoroughly investigate the attack in order to prevent it in the future, "or more importantly build a more robust infrastructure with controls in place to withstand future DoS attacks."

Background: DDoS History and Prevention

A Distributed Denial of Service, or DDoS for short, occurs when a Web site is flooded by traffic in a way that is intended to "make it unavailable to its users," Barb Dybwad of Mashable explains. "Targets are typically hugely popular destinations with a lot to lose."

Technically what happens during a DDoS is that the perpetrator, often a hacker, will send "a flood of external communication requests to the site that at first glance may appear just like legitimate traffic." Dybwad mentions previous attacks dating back to 2000 on sites including Yahoo, eBay and Amazon.

As she suggests, just because DDoS attacks are "nothing new" does not mean they are preventable—yet. "[T]hese attacks are extremely difficult to protect against," Dybwad says, "and tough to handle even once they’re identified. Over time the methodologies have become sophisticated enough to make stemming the floodgates of incoming pings tricky even after a DDoS pattern is discovered." In other words, as the technology of prevention evolves, so, too, does the DDoS technology.

Regular computer users can unwittingly aid DDoS perpetrators if their computers aren't installed with up-to-date anti-malware software, CNET's Larry Magid points out. "[T]he attacking PCs"—those deliberately flooding a site such as Twitter—"are infected with malware that does the dirty work for whoever is behind the attack." 

Marian Merritt, a blogger for Symantec, makers of Norton Internet Security and other related products, summarizes how DDoS attacks have evolved:

"In the original DOS days, the work of pinging a domain over and over might have been from a single hacker or a small team of hackers. By using tools or networks of infected computers, the hacker can now summon the distributed power of hundreds or thousands of machines to slam the victim site with domain requests, overloading the routers and servers and effectively shutting the site down." Merritt recommends security tips in the same blog post.

Reference: Internet Security

FindingDulcinea's Web Guide to Internet Security provides basic information and insight into Internet security, and points you to helpful sites on spyware, malware, indentity theft protection, online safety for kids, wireless security, safe online banking and more.
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