"These ransomware attacks have been on the rise over the last three years, it wasn't exactly something that was a shock - what was surprising is the scale of this one".
By drawing attention to the shortcomings of legacy computer systems, WannaCry could indirectly drive more demand to companies such as Google and Microsoft that have built massive cloud computing businesses, said Stewart Baker, a former general counsel at the National Security Agency.
Sir Michael said: "That is a ten-year programme and part of the cost of that programme has to come from efficiency savings, getting rid for example of land and barracks and buildings that we don't need, being more efficient in the way that we work".
"So there's a good chance they are going to do it... maybe not this weekend, but quite likely on Monday morning".
The anonymous specialist, known only as MalwareTech, is said to have prevented more than 100,000 computers across the globe from being infected.
In the United Kingdom, critics said the government had known about the threat of a cyber attack for some time, but hospitals had not made the right upgrades to protect themselves.
The British government said 48 of 248 health service trusts - the bodies that run the hospitals - in England had been impacted by Friday's attack.
The red-coloured "critical alert" was issued by the Computer Emergency Response Team of India (CERT-In), the nodal agency to combat hacking, phishing and to fortify security- related defences of the Indian Internet domain.
Mr Tehan said Australian business boardrooms needed to be conscious of the impacts of ransomware.
"They're aware of this". The most important thing we can do right now is to be in touch with them, and to offer reassurance and guidance as appropriate. "So they no longer get the security updates they should be".
In Perth, Senator Scott Ludlam warned Australians to keep their computers up to date against such threats and hit out against cyber-weapon creation by the US.
The latest virus attack last week exploits a flaw in a version of Microsoft Windows first identified by USA intelligence.
The malware has wormed its way into thousands of computer systems in an apparent extortion plot, shutting users out unless they coughed up a payment.
The effects were felt across the globe, with Russia's Interior Ministry and companies including Spain's Telefonica, FedEx Corp.in the USA and French carmaker Renault all reporting disruptions. And WannaCry threatens to create even more havoc on Monday when people return to work.
Chris Wysopal of the software security firm Veracode said criminal organizations were probably behind the attack, given how quickly the malware spread.
Russia's interior ministry said some of its computers had been hit by a "virus attack" and that efforts were underway to destroy it.
The attackers could also hit back with a variant of the malware that does not have a provision for the "kill switch" found by a researcher to stem the first round of attacks.
It also tweeted that while version one of the software was stoppable, the subsequent version "will likely remove the flaw".
"In the meantime, we wish to reassure patients that your GP will be there for you as usual if you are taken ill and that you will receive the best possible care from the NHS, despite the current difficulties".style="text-align: center;"