The majority of the attacks targeted Russia, Ukraine and Taiwan.
A large-scale cyber attack has plunged the United Kingdom's health service into chaos.
US President Donald Trump has ordered his homeland security adviser, Tom Bossert, to hold an emergency meeting to assess the threat posed by the global computer ransomware attack.
Security experts tempered the alarm bells by saying that widespread attacks are tough to pull off.
"It was actually partly accidental", he told the BBC, after spending the night investigating.
The group claimed it was stolen from a repository of National Security Agency hacking tools.
Huss shared the information with a British researcher, known as Malware Tech, who had unexpectedly stopped the malware's spread by registering a domain name. "We've seen that the slowdown of the infection rate over Friday night, after a temporary fix around it, has now been overcome by a second variation the criminals have released". Now, when the code pinged that domain, it turned out to be registered and the ransomware would not activate.
But the kill switch couldn't help those already infected.
Michael Gazeley, managing director of cybersecurity firm Network Box, told CNN that the danger is far from over and that a company's security patch on Saturday might not still work by Monday.
"IT managers need to be extremely aware that new variants of this ransomware attack are being launched nearly hourly, so they can't just check that their computer systems are protected, then relax, assuming everything will stay that way", he said.
According to Europol the ransomware attack that affected 45 NHS divisions was part of a worldwide incident that has hit more than 100,000 organizations in 150 countries.
Wainwright said Europol was working with the Federal Bureau of Investigation in the United States to track down those responsible, saying that more than one person was likely behind it.
Friday's attack was the latest in the growing menace of ransomware in which hackers deliver files to computers that automatically encrypt their data, making it unusable until a ransom is paid. Cybersecurity experts say they are still trying to determine who is behind the WannaCry ransomware.
This one worked because of a "perfect storm" of conditions, including a known and highly unsafe security hole in Microsoft Windows, tardy users who did not apply Microsoft's March software fix, and malware created to spread quickly once inside university, business or government networks. That program spread much more quickly than expected, soon choking and crashing machines across the internet. It was benign because it contained a flaw that prevented it from taking over computers and demanding ransom to unlock files but other more malicious ones will likely pop up."We haven't fully dodged this bullet at all until we're patched against the vulnerability itself", Kalember said.
The instigators of the virus demanded computer owners pay $300 to $600 in Bitcoin to retrieve their encrypted data. Fortune reported Thursday that the price of bitcoin was at an all-time high. "We were talking online about how the biggest cyberattack of the year happens and we're both off".
"The affected company doesn't fall under critical infrastructure, it's not a medical or health service and it is not a big company", he said.
While hospitals were not the target of the WannaCry ransomware strain Friday, they were among the most infected as they often lack budgets to defend their online systems, and once their networks are down, thousands of patients lives may be put at risk.
"The difficulty is, of course, there are literally hundreds of instances of ransomware in Australia each week, so we're now seeking to confirm whether these are examples of the particular ransomware that has caused so much havoc for example in the United Kingdom", she told reporters in Cairns. "Because they could have done something ages ago to get this problem fixed, and they didn't do it".