China accused of launching four-day cyber attack on US coding website GitHub

GitHub, the world's largest code host, is recovering from a four-day cyber siege, reportedly the handiwork of Chinese censorship authorities.

The massive distributed denial of service attack - better known as DDoS - was launched on Thursday and continued to affect the site until Sunday when GitHub said it had gotten to grips with it.

The internet traffic onslaught prevented users from accessing the site for extended periods of the attack.

It's thought that the attack, which GitHub said was the largest in its history, originated in China, with a report in the Wall Street Journal saying it was an attempt to shutdown anti-censorship tools.

Security experts told the Journal that the traffic was directed via Baidu, China's largest search engine, to two GitHub pages that linked to sites banned in China.

The sites are Greatfire.org, which keeps tabs on Chinese online censorship activity and suggests ways of circumventing restrictions, and CN-NYTimes, the Chinese-language version of banned US newspaper New York Times.

A spokesman for Baidu denied claims that the search engine was involved, saying an internal investigation concluded that it was neither a security problems or hack attack.

The spokesman said: "“We have notified other security organisations and are working to get to the bottom of this."

GitHub, which offers social coding tools for developers, said in a blogpost the attack involved "a wide combination of attack vectors".

It continued: "These include every vector we've seen in previous attacks as well as some sophisticated new techniques that use the web browsers of unsuspecting, uninvolved people to flood github.com with high levels of traffic.

"Based on reports we've received, we believe the intent of this attack is to convince us to remove a specific class of content."