Earlier this month, a federal grand jury returned an indictment charging a Chinese national and another individual as part of an extremely sophisticated hacking group operating in China that targeted large businesses in the United States, including health insurer Anthem. The indictment stemmed from an investigation by the FBI in which Anthem cooperated, earning praise for its assistance.

According to a news release from the U.S. Department of Justice, the indictment alleges that Fujie Wang (a/k/a Dennis Wang) and other members of the hacking group, including another individual charged as “John Doe,” conducted a campaign of intrusions into U.S.-based computer systems. They gained entry into the systems of Anthem as well as three other U.S. businesses, which were not specifically identified. Beginning in February 2014 and continuing into 2015, the defendants used very sophisticated techniques to hack into the companies’ networks and then installed malware and tools on the systems, through which they identified and stole data of interest on the compromised computers, including personally identifiable information and confidential business information.

The indictment indicates that the techniques utilized by the hackers included sending specially-tailored “spearfishing” emails with embedded hyperlinks to company employees. If the links were accessed, a file was downloaded that deployed malware and installed a backdoor tool that would provide remote access to the computer system through a server controlled by the hackers. The hackers then used software to collect the information they wanted and stole it by placing it into encrypted archive files which were sent through multiple computers to China. They also allegedly then deleted the encrypted files from the victims’ computer networks in an attempt to avoid detection.

Charges in an indictment are merely allegations, and defendants are presumed innocent until proven guilty in court. The government has indicated its commitment to prosecuting the case and bringing those responsible to justice.