The virus that hit the NHS in England and Scotland, known as Wanna Decryptor or WannaCry, has infected 200,000 machines in 150 countries since Friday.
"We've never seen anything like this", he said.
British technology experts worked through the night to patch the computer systems of the health service after the ransomware worm forced dozens of hospitals to cancel some operations and appointments, Security Minister Ben Wallace said on May 15.
He said "the level of criminal activity is at the lower end of the range that we had anticipated". Two big telecoms companies, Telefónica of Spain and Megafon of Russian Federation, were also hit, as was Japanese carmaker Nissan in the United Kingdom.
"In this sense, the WannaCrypt attack is a wake-up call for all of us".
"Unfortunately, there are some very smart and bad people out there who spend their times trying to make things worse for us, and this is not game over for us", he said. Seven of the 47 affected trusts were still having IT problems Monday.
But no one anticipated simply registering the domain would halt the spread of this attack.
The researcher in question become aware of the campaign at 14:30 on Friday and although they were not surprised by a public sector system being hit - hospitals are regular targets for ransomware - but the simultaneous nature of the attack suggested it was huge. "It is so visible and so global".
Nissan: The carmaker said in a statement that "some Nissan entities were recently targeted" but "there has been no major impact on our business".
Patients awaiting non-emergency procedures tomorrow were warned they could also be affected, as a NHS boss rounded on the hackers.
But Putin said they had anything to do with the attack, which hit hundreds of thousands of computers.
"Such vulnerabilities were fixed by computer company Microsoft for any computers using software after Windows XP".
Hospitals have continued to treat patients throughout the weekend and are working hard to return to normal services. In this instance patients may experience some delays in getting through.
Microsoft has released a patch for unsupported operating systems such Windows XP in a bid to halt the spread of the attack. Infected computers demanded users pay $300 (£230) in Bitcoin to retrieve the encrypted documents.
IT systems at Provide were interrupted by the ransomeware on Friday.
Mr Biggs said: "It is vital that NHS trusts invest adequately in cyber security as they seek to protect themselves against future attacks". We are being careful and taking precautions to prevent anything being spread.
As early as March, Microsoft had issued a "critical" free software update that would fix the vulnerability.
The president of Microsoft laid some of the blame at the feet of the USA government.
Brad Smith, Microsoft's president and chief legal officer, said in a blog post on Sunday that the culprits had used a code developed by the US National Security Agency.
Experts and governments alike warn against ceding to the demands and Wainwright said few victims so far had been paying up.
Tom Bossert, a homeland security adviser to President Donald Trump, said "criminals" were responsible, not the USA government.
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