May 13, 2017 - 10:49 AMT
Major cyber attack infects tens of thousands of computers worldwide

A global cyber attack leveraging hacking tools believed to have been developed by the U.S. National Security Agency has infected tens of thousands of computers in nearly 100 countries, disrupting Britain's health system and global shipper FedEx, Reuters said.

Cyber extortionists tricked victims into opening malicious malware attachments to spam emails that appeared to contain invoices, job offers, security warnings and other legitimate files.

The ransomware encrypted data on the computers, demanding payments of $300 to $600 to restore access. Security researchers said they observed some victims paying via the digital currency bitcoin, though they did not know what percent had given in to the extortionists.

Researchers with security software maker Avast said they had observed 57,000 infections in 99 countries, with Russia, Ukraine and Taiwan the top targets.

Asian countries reported no major breaches on Saturday, May 13, but officials in the region were scrambling to check and the full extent of the damage may not be known for some time.

China's official Xinhua news agency said some secondary schools and universities had been affected, without specifying how many or identifying them.

The most disruptive attacks were reported in Britain, where hospitals and clinics were forced to turn away patients after losing access to computers on Friday.

International shipper FedEx Corp said some of its Windows computers were also infected. "We are implementing remediation steps as quickly as possible," it said in a statement.