Rob Wainwright, Executive Director of Europol, says "Now is the time for all sectors to take note of cyber security as a huge strategic concern".
NZ cyber security officials say they'll be staying vigilant with the working week starting tomorrow.
U.S. Treasury Secretary Steven Mnuchin, at a meeting in Italy, said Saturday the attack was a reminder of the importance of cybersecurity.
Europol's Wainwright underscored the point Sunday. It affects Microsoft machines running older versions of Windows, holding users' files for ransom. But computers and networks that hadn't updated their systems were still at risk.
Before Friday's attack, Microsoft had made fixes for older systems, such as 2001's Windows XP, available only to those who paid extra for extended technical support.
Cyber security experts fear more havoc on Monday as people return to work and unlock their computers.
Who is to blame for the massive ransomware attack? He said it could spread a number of ways.
He added: "It's not a massively sophisticated attack".
Friday's attack escalated via combined ransomware techniques with code that spread through recently uncovered weaknesses in Microsoft (MSFT) Windows and, although Microsoft had repaired the vulnerability, computers worldwide had not been patched and fell victim to the hackers.
The advice from security experts and the National Crime Agency (NCA) is do not pay the ransom.
The global "ransomware" cyberattack hit computers at 600 locations in Japan, but appeared to cause no major problems as people in the country started their workday Monday, even as the attack caused chaos elsewhere.
WannaCry locks the data on a computer system and leaves the user with two files: instructions on what to do and the Wanna Decryptor program.
United Kingdom defense secretary Michael Fallon said Sunday that Britain's nuclear submarines were safe from cyberattack.
Sky News has learned that trusts in England were sent details of a security patch last month to protect themselves from such an attack. This particular application is what we call the WannaCry Ransomware, which asks for at least $300 from the user. Here's how to turn automatic updates on.
A hacking group called Shadow Brokers released the malware in April, claiming to have discovered the flaw from the NSA, Kaspersky said.
- King Arthur makes lacklustre impact at US box office
- Ransomware attack hit 200000 in at least 150 countries
- New cyber chaos appears to have been avoided, says Europol
- Dumfries and Galloway NHS hit in cyber attack
- Xi: New initiative needs to reject protectionism
- Spurs embarrass Rockets, advance to face Warriors
- Penguins knot series with 1-0 Game 2 victory over Senators
- Nadal cruises into Madrid final
- McKinley Explains Vote for American Health Care Act
- North Korea: New long-range missile can carry heavy nuke