Former government officials with knowledge of the breach said attackers successfully accessed a database that flagged Gmail accounts marked for court-ordered wiretaps. Such information would have given attackers insight into active investigations being conducted by the FBI and other law enforcement agencies that involved undercover Chinese operatives.
"Knowing that you were subjects of an investigation allows them to take steps to destroy information, get people out of the country," a former U.S. government official with knowledge of the breach told the Washington Post, which first reported the news. But the official cautioned that the attack also could have been a subterfuge operation by Chinese intelligence agencies designed to trick U.S. intelligence agencies into believing false or misleading information.
[ What are the facts behind Chinese hacks? Read China Denies U.S. Hacking Accusations: 6 Facts. ]
The new Operation Aurora revelations came after a Microsoft official last month disclosed that his company had apparently been targeted by the same attackers -- unsuccessfully, he said -- at the same time as Google.
"What we found was the attackers were actually looking for the accounts that we had lawful wiretap orders on," David W. Aucsmith, senior director of Microsoft's Institute for Advanced Technology, told a government IT conference hosted by Microsoft in Redmond, Wash., last month, CIO.com first reported.
"So if you think about this, this is brilliant counter-intelligence. You have two choices: If you want to find out if your agents, if you will, have been discovered, you can try to break into the FBI to find out that way," said Aucsmith. "Presumably that's difficult. Or you can break into the people that the courts have served paper on and see if you can find it that way. That's essentially what we think they were trolling for, at least in our case."
Microsoft's recounting of the attacks stood in sharp contrast to Google's disclosure, published in early January 2010. "In mid-December , we detected a highly sophisticated and targeted attack on our corporate infrastructure originating from China that resulted in the theft of intellectual property from Google," said a blog post by Google's chief legal officer, David Drummond.
At the time, having a major business publicly blame the Chinese government for having launched an information security attack against its systems was rare.
The successful attack against Google was dubbed Operation Aurora by security firm McAfee because attackers reportedly employed the Aurora (a.k.a. Hydraq) Trojan horse application. At the time, however, Google said its investigation into the attack found that "at least twenty other large companies from a wide range of businesses -- including the Internet, finance, technology, media and chemical sectors -- have been similarly targeted." Google also disclosed that a second branch of the attack had compromised multiple Chinese and Vietnamese activists' Gmail accounts.
All told, the Operation Aurora attacks reportedly targeted at least 34 companies, including Adobe, Juniper, Rackspace, Symantec, Northrop Grumman, Morgan Stanley and Yahoo.
At the time, Bruce Schneier, chief security technology officer of BT, said that the Google attackers exploited wiretap backdoors mandated by the U.S. government to access the activists' accounts. "In order to comply with government search warrants on user data, Google created a backdoor access system into Gmail accounts. This feature is what the Chinese hackers exploited to gain access," according to Schneier. "Systems like these invite misuse: criminal appropriation, government abuse and stretching by everyone possible to apply to situations that are applicable only by the most tortuous logic."
The Operation Aurora attacks became the basis for what's now known as an advanced persistent threat (APT) attack.
Last year, Symantec reported that the Aurora gang was still at work, and operating with a large budget. "The group seemingly has an unlimited supply of zero-day vulnerabilities," according to Symantec. "The vulnerabilities are used as needed, often within close succession of each other if exposure of the currently used vulnerability is imminent."