The cyberattack against Mitsubishi Electric Corp. began in March last year and originally targeted a server in China, a report by the machinery-maker and major defense contractor says.
The server was hacked on March 18, 2019, and infected with malware that can be controlled remotely, according to a report the company released about its in-house investigation Wednesday.
From there, the hackers then attacked Mitsubishi Electric’s computers in Japan, it said, noting that information related to the Defense Ministry may have been compromised along with other data before the company could completely block the attackers in July.
The company said it was unable to track down the hacker. The cyberattack came to light last month.
The sensitive defense data included documents on equipment performance that were compiled ahead of bidding for a prototype for research, the company said.
Mitsubishi Electric transformed the original paper documents provided by the ministry into electronic files and stored them in a networked computer.
The paper documents should have been kept in a room dedicated for storage, not converted into electronic form, the company acknowledged.
The Defense Ministry is investigating the possibility that other highly confidential data may have been compromised.
Mitsubishi Electric said it has reconfirmed that sensitive information on social infrastructure, confidential information on technologies and important information stated under contracts with clients, was not leaked.