Friday's global cyber-attack has affected more than 200,000 victims in 150 countries, Europol chief Rob Wainwright said on Sunday.
AN AUSTRALIAN business has fallen victim to a global malware attack and there are investigations into two other reports, the federal government says.
But the next ransomware attack could take control over more number of computer systems across the world.
"At this stage it's likely that at least one business has been impacted".
Mr Wainwright said the attack was "unprecedented in its scale" and warned many more people could find themselves affected.
"We're not talking about a government organisation or a hospital or anything like that".
In a post on its website Saturday evening, Britain's National Cyber Security Center said MalwareTech had prevented further infections and "already resulted in preventing over 100,000 potential infections".
"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.
The virus, which took control of users' files, spread to 100 countries, including India, the UK, Spain, France and Russian Federation.
The ransomware attack that affected numerous computers in over 100 countries forced to shut procedures in hospitals, making it hard for them to function normally.
Microsoft released patches last month and on Friday to fix a vulnerability that allowed the worm to spread across networks, a rare and powerful feature that caused infections to surge on Friday.
"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.
A ransomware attack appears to be spreading around the world, leveraging a hacking tool that may have come from the U.S. National Security Agency.
Microsoft said the situation was "painful" and that it was taking "all possible actions to protect our customers".
Images appear on victims' screens demanding payment of $300 (275 euros) in the virtual currency Bitcoin, saying: "Ooops, your files have been encrypted!"
Once it infects one computer within a network, it can spread to all the computers in that network "within seconds", said Israel Levy, the CEO of the cybersecurity firm Bufferzone.
Bishop said departmental level, government level and departmental heads must take necessary steps since it was something they were aware about, Sky News reported.
"Or we could potentially see copycats mimic the delivery or exploit method they used", he said.
Wainwright warned the healthcare sector "in many countries" was particularly vulnerable, but that all organizations should ensure they prioritize cyber security and update their systems.
"Once we get to the bottom of this one, we'll make sure that this is available to people as well", he said. The ransomware exploits older versions of Microsoft's operating system software, such as Windows XP.
In the United States, where FedEx Corp. reported that its Windows computers were "experiencing interference" from malware - not specifying if it had been hit by the ransomware - other effects of the ransomware were not readily apparent.