“The cyber-attack manipulated international web traffic intended for one of China’s biggest web services companies and turned it into malicious traffic directed at US sites,” Rathke told a news briefing.
He said the United States asked Chinese authorities to investigate the cyber-attackand report its findings.
The Chinese government has repeatedly denied it has anything to do with hacking.
China’s “Great Cannon” is a distinct cyber-attack tool that hijacks traffic to or from individual IP addresses and allows China to target “any foreign computer that communicates with any China-based website,” according to an analysis from information technology research group Citizen Lab of Toronto.
Justin W. Clarke, a senior security researcher at Cylance cyber-security firm, called the Great Cannon a “potentially devastating tool” that is “one of the biggest cyber weapons that has become publicly known.”
“Every user in China could be potentially weaponized by their government,” he said.
After attacks that included the December hacking of Sony Pictures attributed to North Korea, the United States wanted to send a message, said cyber-security expert James Lewis, a senior fellow at the Center for Strategic and International Studies.
“This was China going outside China to stifle dissent and coming into the US to do it,” Lewis said. “So coming on the heels of Sony … they feel they have to send a really strong message: ‘You guys are really crossing the line.'”
In March, US coding site GitHub said it was deflecting most of the traffic from a days-long cyber-attack that had caused intermittent outages for the social coding site, with the Wall Street Journal citing China as the source of the attack.
The attackers pushed massive amounts of traffic to GitHub by redirecting overseas users of the popular Chinese search engine Baidu Inc, the Journal reported.
GitHub supplies coding tools for developers and calls itself the world’s largest code host.
The newspaper said they targeted two GitHub pages that link to copies of websites banned in China – a New York Times Co Mandarin-language site and Greatfire.org, which helps Chinese users circumvent government censorship.