The global "ransomware" cyberattack hit computers at 600 locations in Japan, but appeared to cause no major problems as Japanese started their workday Monday even as the attack caused chaos elsewhere.
Nissan Motor Co. confirmed some units had been targeted, but there was no major impact on its business.
Hitachi spokeswoman Yuko Tainiuchi said emails were slow or not getting delivered, and files could not be opened. The company believes the problems are related to the ransomware attack, although no ransom appears to have been demanded so far. They were installing software to fix the problems.
The Japan Computer Emergency Response Team Coordination Center, a nonprofit providing support for computer attacks, said 2,000 computers at 600 locations in Japan were reported affected so far, citing an affiliate foreign security organization that it cannot identify.
At least one hospital was affected, according to police.
The city of Osaka said its home page suddenly went blank, although email and other problems had not been detected.
"We cannot confirm why this happened, and we are in the middle of investigating," said Hajime Nishikawa of the city hall's IT division.
The attack, known as "WannaCry," paralyzed computers that run Britain's hospital network, Germany's national railway and other companies and government agencies worldwide in what may be the largest online extortion scheme ever.
Japanese Twitter users posted complaints about their computers shutting down and posted photos of the ransom demands on their computer screens.
The attack held users hostage by freezing their computers, popping up a red screen with the words, "Oops, your files have been encrypted!" and demanding money through online bitcoin payment — $300 at first, rising to $600 before it destroys files hours later.
Eiichi Moriya, a cyber security expert and professor at Meiji University, said that most major Japanese companies have already set up safeguards or a "patch" and should avert the attack, so that damage in Japan should be limited compared to other countries.
He noted that many payments were already being made, but warned that paying the ransom did not ensure any fix, and suggested people keep data backups as the attack causes encryptions.
"You are dealing with a criminal," he said. "It's like after a robber enters your home. You can change the locks but what has happened cannot be undone. If someone kidnaps your child, you may pay your ransom but there is no guarantee your child will return."
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