Denial of Service Attack Knocks Out Twitter

In what is believed to be the first major attack of its kind on the social networking site, Twitter has suffered a Denial of Service (DoS) attack overnight.

Although no user data was compromised in the attack, Twitter was inundated with so many requests that it couldn’t respond to legitimate requests thereby denying service to many users. For the non-techies reading this who want to know exactly what a Denial of Service attack is, Dave Taylor has written a very un-geek explanation of it.

The strength of the attack on Twitter was enough to crash the popular micro-blogging site for over 60 minutes and has continued to cause ongoing connectivity problems for Twitter addicts ever since.

The Twitter status page tells the story:

“We are defending against a denial-of-service attack, and will update status again shortly.

Update: the site is back up, but we are continuing to defend against and recover from this attack.

Update (9:46a): As we recover, users will experience some longer load times and slowness. This includes timeouts to API clients. We’re working to get back to 100% as quickly as we can.

Update (4:14p): Site latency has continued to improve, however some web requests continue to fail. This means that some people may be unable to post or follow from the website.”

In their official blog, co-founder @Biz stated today that Twitter staff don’t know or would prefer not to speculate on the motivation behind the DoS event, except to say that it appears to be a single, massively coordinated attack and that many other companies and services were also affected. One of the major services affected was Facebook.

News of the DoS attack spread very quickly and when Twitter finally came back online, the event even spawned its own hashtag #whentwitterwasdown so Twitterholics could humorously share what they were doing during the downtime.

Based on the sheer scale of the event, it appears the attack was a Distributed Denial of Service (DDoS) using trojans or zombie machines. Whatever it was, Twitter has some serious stability issues to iron out as a result.

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