The hunt was on for the culprits behind the assault, which was being described as the biggest cyber ransom attack ever.
State agencies and major companies around the world were left reeling by the attacks which blocked access to files and demanded ransom money, forcing shutdowns of computer systems.
A spokeswoman said the company was "doing what is needed to counter this attack".
It shows we urgently need to explore what steps could be taken to better protect vital systems like this from cyber attacks. Security firms said the attacks had spread to all corners of the globe, with Russia hit the worst, followed by Ukraine, India, and Taiwan, said Kaspersky Lab, a Russian cybersecurity firm.
"The National Security Agency (NSA) is supposed to lead the vulnerability equities process with all the other government agencies gathered round to discuss their interests in the vulnerability, and to weigh the offensive capabilities against defensive concerns for the private sector and US interests", The Guardian quoted Adam Segal, the director of the digital and cyberspace policy program at the Council on Foreign Relations, as saying.
The cyberattack was initially believed to target only hospitals in the United Kingdom, but it turned out to be a worldwide attack, British Prime Minister Theresa May said.
The attack also forced French carmaker Renault to halt its production at sites in France in an effort to stop the malware from spreading.
In the U.S., FedEx Corp. reported that its Windows computers were "experiencing interference" from malware, but wouldn't say if it had been hit by ransomware.
Windows XP - which was released more than 15 years ago - is still used in hospitals across Britain despite it no longer being serviced by Microsoft.
Hometown of ex-FBI Director James Comey reacts to his dismissal
Me". "It does raise a very serious question, whether the president's intent was to subvert the investigation". Tuesday: "This has nothing to do with Russia", White House counselor Kellyanne Conway told CNN.
A spokesman said a "small number" of GP and dental surgeries in Forth Valley had reported problems, while ten Tayside GP practices have been hit. Russia's national railway system said it was attacked but rail operations were unaffected. According to it, ransomware spreads easily when it encounters unpatched or outdated software.
The researcher, tweeting as @MalwareTechBlog, said registering a domain name used by the malware stops it from spreading, though it can not help computers already affected.
The kill switch also couldn't help those already infected. The researcher explained that the attackers may still rewrite the code and relaunch the cycle and urged everyone to promptly patch their systems.
WannaCry is not just a ransomware program, it's also a worm.
Researchers believe spying tools developed by the US National Security Agency were used in the attack that hit worldwide shipper FedEx, disrupted Britain's health system and forced a European carmaker to halt some production lines.
"We are on a downward slope, the infections are extremely few, because the malware is not able to connect to the registered domain", said Vikram Thakur, principal research manager at Symantec, as cited by Deutsche Welle.
"Ransomware becomes particularly nasty when it infects institutions like hospitals, where it can put people's lives in danger", said Kroustek, the Avast analyst.
Several experts believe the cyber attack is linked to a hacker group called The Shadow Brokers-the same group that claimed in April that it had stolen and released malware created by the National Security Agency, NSA. Microsoft swiftly released software "patches" to fix those holes, but many users still haven't installed updates or still use older versions of Windows. That low-cost move redirected the attacks to MalwareTech's server, which operates as a "sinkhole" to keep malware from escaping.
We need to get to the bottom of why the government thought cyber-attacks were not a risk, when a combination of warnings and plain common sense should have told ministers that there is a growing and unsafe threat to our cyber-security.
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