A cyber-attack that has hit 150 countries since Friday should be treated by governments around the world as a “wake-up call”, Microsoft says.
The computing giant said software vulnerabilities hoarded by governments had caused “widespread damage”.
The latest virus exploits a flaw in a version of Microsoft Windows first identified by US intelligence.
There have been warnings of further “ransomware” attacks as people return to work on Monday.
Many firms have had experts working over the weekend to prevent new infections. The virus took control of users’ files and demanded $300 (£230) payments to restore access.
The spread of the virus slowed over the weekend but the respite might only be brief, experts have said. More than 200,000 computers have been affected so far.
But on Monday South Korea said just nine cases of ransomware had been found, giving no further details.
Australian officials said so far only three small-to-medium sized businesses had reported being locked out of their systems while New Zealand’s ministry of business said a small number of unconfirmed incidents were being investigated.
A statement from Microsoft president and chief legal officer Brad Smith on Sunday criticised the way governments store up information about security flaws in computer systems.
“We have seen vulnerabilities stored by the CIA show up on WikiLeaks, and now this vulnerability stolen from the NSA has affected customers around the world,” he wrote.
“An equivalent scenario with conventional weapons would be the US military having some of its Tomahawk missiles stolen.”
He added: “The governments of the world should treat this attack as a wake-up call.”
Microsoft said it had released a Windows security update in March to tackle the problem involved in the latest attack, but many users were yet to run it, reports the BBC.
“As cybercriminals become more sophisticated, there is simply no way for customers to protect themselves against threats unless they update their systems,” Smith said.