Writing on the company's website, Microsoft's president and chief legal officer Brad Smith gave a post-mortem of last Friday's "WannaCrypt" cyber-attack, which spread across the world thanks to a database of exploits stolen from the US' National Security Agency (NSA).
The attack sent the stock prices of Chinese internet security firms soaring in the Shenzhen market. And while Microsoft said it had already released a security update to patch the vulnerability one month earlier, the sequence of events fed speculation that the NSA hadn't told the US tech giant about the security risk until after it had been stolen.
The apparently random attack, called "WannaCry," hit on Friday and spread like wildfire before a malware researcher identified as Marcus Hutchins was able to halt it temporarily a day later, when workers in many companies weren't in their offices.
Security experts said his move bought precious time for organizations seeking to block the attacks.
Organizations around the world spent the weekend trying to recover after being hit by a virus that seeks to seize control of computers until victims pay a ransom.
The companies and government agencies targeted were diverse.
Symantec said the majority of organisations affected were in Europe.
He said it's likely the ransomware will spread to USA firms too.
The attack, known as "WannaCry" had a major impact across Asia as workers there returned to work on Monday, with Chinese state media saying nearly 30,000 institutions there had been infected.
Europol's Wainwright underscored the point Sunday. With that, Microsoft releases a patch for the vulnerability in March.
"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.
Several organizations around the world including the UK's National Health Service (NHS) were greeted by a message informing them that they had to pay $300 in Bitcoin if they wanted access to their files.
Dozens of countries were hit with a huge cyberextortion attack Friday that locked up computers and held users' files for ransom at a multitude of hospitals, companies and government agencies. "If your system requires Windows Updates to receive the patch for this exploit, create new backups after applying the patch".
The Seattle-based tech giant issued guidance for people to protect their systems, while taking the highly unusual step of reissuing security patches first made available in March for Windows XP and other older versions of its operating system. Machines that contained the patch are much less at risk than those that didn't. Use a reputable security software to prevent attacks in the future. Wainwright said Europol did not know the motive.
(AP Photo/Mark Schiefelbein). A screenshot of the warning screen from a purported ransomware attack, as captured by a computer user in Taiwan, is seen on laptop in Beijing, Saturday, May 13, 2017.
And WannaCry has already caused massive disruption around the globe.
Sixteen National Health Service (NHS) organizations in the United Kingdom have been hit, and some of those hospitals have canceled outpatient appointments and told people to avoid emergency departments if possible. Your organization is at risk if you do not update your Windows operating system. But what can you do, as a simple consumer, to protect yourself against such a powerful ransomware attack?
Gas stations: State-run media in China reported that some gas stations saw their digital payment systems shut down, forcing customers to bring cash.
Avast, an global security software firm that claims it has 400 million users worldwide, said the ransomware attacks rose rapidly Saturday to a peak of 57,000 detected intrusions. The main challenge for investigators was the fast-spreading capabilities of the malware, he said, but added that so far, not many people have paid the ransoms that the virus demands. Two big telecom companies, Telefónica (TEF) of Spain and Megafon of Russian Federation, were also hit.