The denial of service (DOS) attacks which knocked Twitter offline and slowed down Facebook response times yesterday may have been designed to target just one individual.

Max Kelly, chief security officer at Facebook, said the problems experienced by those trying to access the two sites, as well as LiveJournal and Blogger, may have been motivated by efforts to silence a Georgian blogger on the one-year anniversary of Georgia's invasion of South Ossetia.

The blogger, who has accounts on all four of the sites under the name 'Cyxymu', was an outspoken critic of the 2008 South Ossetia War, also known as the Russia-Georgia War, which began on August 7 2008.

Is Twitter down

"It was a simultaneous attack across a number of properties targeting him to keep his voice from being heard," Kelly told "We're actively investigating the source of the attacks and we hope to be able to find out the individuals involved in the back end and to take action against them if we can."

A DoS attack is an attempt to make a website or service unavailable to users by flooding the service or site with incoming data requests, such as emails. Motives for DoS attacks vary, but perpetrators mostly target companies with high-profile, highly trafficked websites. Hackers often have a financial or political motivation for such attacks.

However, Twitter has refused to be comment on the motivation for the attacks in its most recent update.

"Twitter has been working closely with other companies and services affected by what appears to be a single, massively coordinated attack. As to the motivation behind this event, we prefer not to speculate," says the official Twitter blog.
Twitter was still down at 9am GMT Friday morning.