Cybersecurity experts have said the majority of the attacks targeted Russia, Ukraine and Taiwan.
Several hospitals in London and other parts of England and Scotland were affected and some reportedly halted surgeries amid fears the lives of patients were at risk.
Krishna Chinthapalli, a doctor at Britain's National Hospital for Neurology & Neurosurgery who wrote a paper on cybersecurity for the British Medical Journal, said many British hospitals still use Windows XP software, introduced in 2001.
That was the chilling prediction made yesterday by Ron Wainwright, the English-born head of the EU's crimefighting organisation Europol.
Tech staffs around the world worked around the clock this weekend to protect computers and patch networks to block the computer hack whose name sounds like a pop song - "WannaCry" - as analysts warned the global ransomware attack could be just the first of a new wave of strikes by computer criminals.
"Very few banks if any have been affected because they've learned from painful experience of being the number one target for cybercrime", he said on ITV's Peston on Sunday program.
Ransomware locks computers and encrypts the data stored on it and also prevents apps and software from running. A group of hackers leaked the code for exploiting that bug earlier this year, saying it was taken from the NSA.
Moors murderer Ian Brady dead at 79
Caroline Cairns posted: 'Rest in Hell Ian Brady, feel for the family of Keith Bennett who never found out where he was buried'. The killings became known as the Moors Murders, because four of the five children's bodies were dumped in the south Pennines.
Rugby World Cup 2019 pools drawn in Japan
Romania are now in the "Europe 1" slot but qualification will not be determined until next year's Rugby Europe Championship. The draw featured the 12 teams that had booked places courtesy of a top-three pool finish at the 2015 World Cup in England .
Melissa McCarthy adds spice (and Spicer) as host of 'SNL'
When Spicer and the White House's lack of credibility are the central focus of an SNL sketch , the problem has gone mainstream. Che's Holt asked "Trump" about how some had drawn comparisons between Trump and Richard Nixon this week.
The patches won't do any good for machines that have already been hit.
Europol provides free decryption downloads for most ransomware already detected, though not yet for this particular attack.
NHS Grampian said it remains "completely confident" no patient data was accessed in the ransomware attack, which hit 13 health boards across the country and countless nationwide, leaving some with a backlog of postponed appointments to contend with. Robinson, in an interview by e-mail, said he calculated the total based on payments tracked to bitcoin addresses specified in the ransom demands.
In a blog post on Saturday, MalwareTech explained he returned from lunch with a friend on Friday and learned that networks across Britain's health system had been hit by ransomware, tipping him off that "this was something big".
While a United Kingdom security researcher managed to stop the spread of the virus, hackers have issued new versions that cybersecurity organizations are trying to counter and stamp out. State media reported that digital payment systems at some gas stations were offline, forcing customers to pay cash.
Foreign Minister Julie Bishop previously said authorities were working to validate if reports of cyber attacks in the country were linked to the global attack. In 2000, a Filipino computer graduate unleashed the "Love Bug" virus that wreaked havoc in at least 20 countries and caused losses estimated at up to $10 billion. The ransomware appeared to have hit some 100,000 systems, more than half in Russian Federation, according to a tweet yesterday by malware researcher Jakub Kroustek.
"However, we must remain particularly vigilant against further incidents and the Scottish Government is taking action to enhance security, including contacting over 120 public bodies to ensure they have appropriate defences in place". As an additional "defense-in-depth" measure, keep up-to-date anti-malware software installed on your machines.