TOKYO, May 15 (Xinhua) -- Hitachi Ltd. said Monday that some of its computer systems were infected by the ransomware virus that struck hundreds of businesses and organization globally over the weekend.
The Tokyo-based, multinational corporation said it had problems sending and receiving emails as well as opening email attachments, and that it was currently investigating which of its devices domestically and overseas had been infected.
Hitachi said it first noticed abnormalities in its system over the weekend, but it had managed to restore some of the files encrypted by the ransomware virus.
The ransomware virus encrypts computer files and locks them, making them inaccessible to the user until the user pays a ransom within a specified timeframe, with the ransom amount increasing if the deadline is not met.
A global cyber attack using the ransomware virus affected some 150 countries over the weekend, with Britain and its National Health Service particularly hard hit.
Hitachi U.K., which has a number of data centers in and outside of London as well as a sizable footprint in Europe, was struck by the virus.
Other Japanese companies that were affected by the virus included Nissan Motor Co's British plant and East Japan Railway Co. said it experienced localized issues with its system.
Other isolated incidents were reported in Japan and the government has set up a crisis management liaison office to deal with current and further cyber attacks using the ransomware virus.
The ransomware virus works by exploiting a weakness first discovered by the United States' National Security Agency in older versions of Microsoft Windows operating system.
Once an infected email attachment is opened, the encrypted, compressed file opens and the malware infects the system and propagates the virus.
Microsoft said an update to its operating system had addressed this problem and a software patch can be installed to protect against the virus.
