Chinese hackers compromised the networks of five European ministries through a spear phishing campaign during September's G20 Summit, according to experts.
Staff at the ministries, which include Portugal and the Czech Republic, were sent bogus emails containing malicious attachments, including one titled "US_military_options_in_Syria," according to a report by Reuters.
Researchers at security firm FireEye exposed the attacks after monitoring the hackers' main computer server for about a week in August. They eventually lost access when the group switched servers.
Because Chinese was the default language used on both their control servers and on the machines used to test the malicious code, experts determined the hackers' origin.
While FireEye could not tie the attacks to a specific group, some security experts speculate it was a state-sponsored campaign, The New York Times reported on Tuesday.