Photo/Illutration The Mitsubishi Electric Corp. logo (Asahi Shimbun file photo)

A June 2019 cyberattack on Mitsubishi Electric Corp. compromised data that constituted the first-ever publicly acknowledged leak of sensitive national security information in Japan, the Defense Ministry admitted.

The ministry, releasing its findings Dec. 24 into its probe of the 59 cases, said nearly 20,000 files were accessed. It added that it has since taken steps to address sabotage of this nature and issued a verbal warning Dec. 22 to Mitsubishi Electric, a leading electronics equipment maker deeply involved in defense, infrastructure and transportation projects.

The company more recently had been in the news for shoddy testing of various equipment that led to disciplinary action being taken against 12 current and former executives.

The Asahi Shimbun broke the report of the stunning cyberattack in January 2020 and Mitsubishi Electric officials suspected a Chinese hacking group. The following month, the Defense Ministry acknowledged that the incident involved three cases of a sensitive nature related to defense equipment.

But in its latest revelation, the ministry disclosed that nearly 20,000 leaked data files contained defense-related information. 

It admitted that the leak of 59 of those data files had a grave effect on national security. However, it refused to divulge the specific contents of the data files on grounds they contained sensitive information.

“This is the first case where authorities have publicly acknowledged a leak by hackers of information regarding threats to national security,” a Cabinet Secretariat source said, 

Mitsubishi Electric has a close relationship with the Defense Ministry and is contracted to work on projects worth about 100 billion yen ($874 million) a year. Among those in which the company has been involved are the manufacture as well as research and development of specialized radar equipment.

Defense Ministry officials said they instructed Mitsubishi Electric to be more vigilant in its handling and protection of defense-related information.

Company officials said they were warned about deficient handling of information in three of the 59 cases. In those three cases, only a paper trail should have been left, but the company inexplicably inputted the information into its computer system, rendering it vulnerable to hackers.

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