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The US Justice Department charged three Chinese computer security experts on Monday with hacking and stealing materials from Moody's Analytics, Siemens, and Trimple, a GPS technology firm.
The three were associated with Guangdong-based Guangzhou Boyu Information Technology Company, known as Boyusec, which some Western security analysts allege has links to the Chinese Ministry of State Security.
The indictment named Boyusec co-founder Wu Yingzhuo, executive director Dong Hao, and Xia Lei, an employee.
It said they hacked the email server of Moody's Analytics in 2011, obtaining access to the emails of a person described as a high-profile economist who represented the Moody's brand -- a description that matches Moody's chief economist Mark Zandi.
Moody's did not confirm or deny that but said it had "worked closely" with the investigation, and had not lost any customer or employee data to the hackers.
In 2014 the three Chinese hackers broke into German industrial giant Siemens' computer networks, stealing large amounts of files and data from its energy, technology and transportation businesses, according to the US indictment.
It added that in 2015-2016 they stole newly developed hardware and software information from a new global satellite navigation system being developed by Trimble.
The three were charged with computer fraud, wire fraud, identity theft, and theft of trade secrets.
The indictment did not say what Boyusec did with the information, some of which had clear commercial value.
"Once again, the Justice Department and the FBI have demonstrated that hackers around the world who are seeking to steal our companies' most sensitive and valuable information can and will be exposed and held accountable," said Acting Assistant Attorney General Dana Boente.