U.S. coding site GitHub said it was deflecting most of the traffic from a days-long cyberattack that had caused intermittent outages for the social coding site, with The Wall Street Journal citing China as the source of the attack.
"Eighty-seven hours in, our mitigation is deflecting most attack traffic," the GitHub Status account said in a tweet on Sunday. "We're aware of intermittent issues and continue to adapt our response."
GitHub supplies coding tools for developers and calls itself the world's largest code host.
The attackers paralyzed the site at times by using distributed denial of service, or DDoS, attacks, a technique commonly used to disrupt websites and computer networks, according to The Wall Street Journal.
They pushed massive amounts of traffic to GitHub by redirecting overseas users of the popular Chinese search engine Baidu Inc, according to the Wall Street Journal.
The newspaper said they targeted two GitHub pages that link to copies of websites banned in China - a Mandarin-language site from The New York Times and Greatfire.org, which helps Chinese users circumvent government censorship.
A Beijing-based Baidu spokesman said a thorough investigation had determined it was neither a security problem on Baidu's side nor a hacking attack.
"We have notified other security organizations and are working to get to the bottom of this," said the spokesman.
On its blog, GitHub said the attack began early on Thursday and involved "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."
GitHub said it believed the intent of the attack was to convince the company to remove a specific class of content.
The Chinese government has repeatedly denied it has anything to do with hacking.
Asked about the report, Chinese Foreign Ministry spokeswoman Hua Chunying said China itself was one of the world's largest victims of hacking and called for international dialogue to tackle the issue.