Experts were urging organisations and companies to immediately update older Microsoft operating systems, such as Windows XP, with a patch released by Microsoft to limit vulnerability to a more powerful version of the malware - or to future versions that can not be stopped.
Putin said that the attack has not caused any significant damage to his country, however security firm Kapersky has suggested that Russian Federation has been one of the worst hit.
He argued there should be "a new requirement for governments to report vulnerabilities to vendors, rather than stockpile, sell, or exploit them".
It says the latest virus exploits a flaw in Microsoft Windows identified by, and stolen from, U.S. intelligence.
But then Microsoft also needs to consider what obligation it has to update all users - not just the ones who pay extra for security on older systems. It's ransomware and stops you from accessing any files on the "infected" computer until you pay the ransom. However, he said it's only a matter of time before a malevolent version exists.
Carmaker Renault said one of its French plants, which employs 3,500 people, wasn't reopening Monday as a "preventative step".
"We haven't fully dodged this bullet at all until we're patched against the vulnerability itself", Kalember said.
The so-called WannaCry ransomware locks access to user files and demands money - in the form of the virtual currency Bitcoin - in order to decrypt them.
The ransomware is known as WannaCry, WanaCrypt0r 2.0 or WCry and it's especially risky because it includes some sort of "worm functionality" that makes it more vicious than a regular ransomware attack. That was "unheard of six months ago", Levy said.
Europol's European Cybercrime Centre said that anyone hit by ransomware should use the unlocking tools provided at NoMoreRansom.org, a free resource developed by Europol in partnership with the Dutch police and other industry partners.
"There's some truth to the idea that people are always going to hack themselves", said Dan Wire, a spokesman for security firm FireEye.
Oregon Health & Science University officials said they hadn't been affected by the ransomware, but they were aware of the attacks on other hospitals.
In the United Kingdom, hospitals were crippled by the cyberattack, which forced operations to be canceled and ambulances to be diverted.
Even more worryingly they claim to have information on the Russian, Chinese, Iranian or North Korean nuclear and missile programs, turning Microsoft's Brad Smith's metaphor about lost Tomahawk missiles worryingly real.
NHS organisations across the country were on alert for a possible recurrence of Friday's cyberattack as staff returned to work on Monday.
"It's this constant battle", said Ryan O'Leary, vice president of WhiteHat Security's threat research center.
Of course, as we always recommend, you should have at least one (if not two) copies of any files you can't afford to lose.
Details about those tools were recently disclosed to the public.
India is vulnerable as a large number of computers in the country run the Microsoft's older operating systems like XP, and have not been updated yet.
Malware researcher danooct1 took one for the team and installed WannaCry on a virtual machine, so we can all see what the malware looks like. The other is to disable a type of software that connects computers to printers and faxes, which the virus exploits, O'Leary added.
The WannaCry exploits used in the attack were stolen from the US National Security Agency, or NSA.style="text-align: center;"