Latest estimates have suggested up to 75,000 individuals across almost 100 countries were affected by the massive cyber attack that locked down computers and demanded a ransom.
A massive hack crippled computers across the world on Saturday in what was described by experts as a cyberattack on an unprecedented in scale.
Two security firms - Kaspersky Lab and Avast - said they had identified the malicious software behind the attack in upward of 70 countries, although both said the attack has hit Russian Federation hardest.
A total of 48 NHS trusts were hit by Friday's cyber-attack, of which all but six are now back to normal, Home Secretary Amber Rudd has said.
WannaCrypt had hit at least 45,000 computers spread over 74 countries demanding a $300 ransom in Bitcoins to restore access to these devices and the information inside. The ransomware was created to repeatedly contact an unregistered domain in its code.
Chris Wysopal of the software security firm Veracode said criminal organizations were probably behind the attack, given how quickly the malware spread.
"Initially someone had reported the wrong way round that we had caused the infection by registering the domain, so I had a mini freak out until I realised it was actually the other way around and we had stopped it", MalwareTech tells The Guardian.
However, a hacker could change the code to remove the domain and try the ransomware attack again.
Europol, the European Union's police agency, said the onslaught was at "an unprecedented level and will require a complex worldwide investigation to identify the culprits".
The U.K.'s National Cyber Security Center says it's working with both the digital office of the NHS and law enforcement.
"This week's incident emphasises the importance for all of us, the public and private sectors as well as the general public, to have the appropriate measures in place to protect against these kinds of attack".
Huss says it is very likely we will see another attack using the exploit, even as early as Monday.
"I believe many companies have not yet noticed", said William Saito, a cyber security adviser to Japan's government. Portions of the spy agency's sophisticated cyber arsenal have been leaked online in recent months.
They're running Windows XP, an operating system first released in September 2001, and which Microsoft itself gave up supporting in 2014; it has been kept on life support by extra payments to the company, but the Department of Health stopped making those in 2015. Users who make it a point to update their systems have some level of protection against this ransomware. Attackers have reportedly demanded Bitcoin payments of £230 to unlock NHS IT systems. It initially said 16 NHS organizations had reported being hit, and more reports came in as the day went on. The NHS said in a statement on Saturday that there was no evidence that patient information had been compromised.
It was also believed that "WannaCry" works by taking advantage of a flaw in Windows that the NSA knew about, but kept secret.
"Global internet security has reached a moment of emergency", Qihoo360 warned.
Police said they had not been made aware of any attacks in New Zealand and the briefing to the ministry was a precaution.
But the kill switch couldn't help those already infected.
Jan Op Gen Oorth, spokesman for the Netherlands-based Europol, said the number of individuals who have fallen victim to the cyberextortion attack could be much higher. When asked to confirm that Wana Decryptor has struck in the USA, and at what scale, Acting Deputy Press Secretary Scott McConnell did not provide specifics.
The assault is part of an attack that has affected organizations in more than 70 countries, including the United States, China, Russia and Spain, disrupting power and telephone companies. Windows machines that are up-to-date are safe from this ransomware.