But many corporations don't automatically update their systems, because Windows updates can screw up their legacy software programs.
The cyberattack paralyzed computers that run Britain's hospital network, Germany's national railway and scores of other companies and government agencies worldwide.
Mr Hunt has come under fire for failing to appear in public since the attack, which hit 47 trusts in England and 13 Scottish health boards.
The organization predicts that the problem could be "at a significant scale" because some infected machines haven't yet been detected, and existing infections can spread within networks.
"We could potentially see copycats mimic the delivery or exploit method they used", he said.
Lynne Owens, director-general of Britain's National Crime Agency, said there was no indication of a second surge of the cyberattack, "But that doesn't mean there won't be one". And that's for a simple reason: Individuals and organizations alike are fundamentally bad about keeping their computers up-to-date with security fixes.
Tehan declined to provide details on the three affected companies, but said the first Australian company reported as hit was not "a government organisation or a hospital or anything like that".
Friday, May 12, saw a cyberattack of global proportions when a ransomware popped up in computers across the globe.
Assuming that a lot of Windows 7 and Windows 8.1 users don't have Microsoft Security Essentials or Windows Defender enabled, they could be open to attack.
His move may have saved governments and companies millions of dollars and slowed the outbreak before USA -based computers were more widely infected.
"We need the tech sector, customers, and governments to work together to protect against cybersecurity attacks". The attack on Britain's NHS was potentially the most devastating as thousands of patients' appointments were cancelled, ambulances rerouted, records lost and chaos followed, despite the warnings delivered, some as recently as past year, on the vulnerability of outdated systems.
The attack held users hostage by freezing their computers, encrypting their data and demanding money through online bitcoin payment - $300 at first, rising to $600 before it destroys files hours later. Brad Smith criticized USA intelligence agencies, including the CIA and National Security Agency, for "stockpiling" software code that can be used by hackers. The NSA tools were stolen by hackers and dumped on the internet.
Tom Bossert, a homeland security adviser to President Donald Trump, said "criminals" were responsible, not the US government.
But experts and government alike warn against ceding to the hackers' demands.
Bossert told ABC's "Good Morning America" that the attack is something that "for right now, we've got under control" in the United States. So far, not many people have paid the ransom demanded by the malware, Europol spokesman Jan Op Gen Oorth told The Associated Press.
Finally, Wainwright praised the work of banks in defending themselves against cybercrime after confirming that "very few banks in Europe, if any, have been affected by this attack, because they have learned from the painful experience of being the number one objective" of this type of computer attacks.
"If there is a silver lining to it, you're not out a million dollars", he said.