The unprecedented global cyberattack has hit more than 200,000 victims in scores of countries, Europol said Sunday, warning that the situation could escalate when people return to work.
This is already believed to be the biggest online extortion attack ever recorded, disrupting computers that run factories, banks, government agencies and transport systems in nations as diverse as Russia, Ukraine, Brazil, Spain, India and the US.
"We have been cornered for some time that the healthcare sector in many countries are particularly vulnerable".
"The global reach is unprecedented", Wainwright says.
Many jobs can be done using software everyone can buy, but some businesses need programs that perform very specific jobs - so they build their own.
"While there is now no suggestion that systems within Northern Ireland have been targeted, we remain conscious that we must act to ensure the integrity of cyber networks and take appropriate action to reduce the threat posed by cyber criminals". I am anxious about how the numbers will continue to grow when people go to work and turn on their machines on Monday morning.
As almost 45 NHS organisations from London to Scotland were hit in the "ransomware" attack on Friday, patients of the state-funded countrywide service faced chaos as appointments and surgeries had to be cancelled.
The unique virus type known as ransomware locks computer screens with a message demanding $300 worth of bitcoins - a special type of online currency - to unlock the systems.
However, Mr Wainwright said that so far "remarkably few" payments had been made by victims of the attack.
The PSNI has said it has been liaising with relevant agencies "to ensure that here in Northern Ireland we are adequately briefed and prepared for the possibility of any potential similar incident".
Meanwhile, the New Zealand government's cyber emergency response team (CERT) is looking into the attack here.
"It only guarantees that the malicious actors receive the victim's money, and in some cases, their banking information".
The culprits used a digital code believed to have been developed by the US National Security Agency - and subsequently leaked as part of a document dump, according to researchers at the Moscow-based computer security firm Kaspersky Lab.
This exploit - known as EternalBlue - was stolen by a group of hackers known as The Shadow Brokers, who made it freely available in April, saying it was a "protest" about US President Donald Trump.
Mr Wainwright said that the ransomware was being combined with a worm application allowing the "infection of one computer to quickly spread across the networks".
The attack therefore spread faster than previous, smaller-scale ransomware attacks. In 2016, Hollywood Presbyterian Medical Center in California said it had paid a $17,000 ransom to regain control of its computers from hackers.
The 22-year-old told the BBC it was very important for people to patch their systems as soon as possible.
In Russia, government agencies insisted that all attacks had been resolved.
Friday's cyber-attack has affected more than 200,000 victims in 150 countries, Europol chief Rob Wainwright says.
A cybersecurity expert says the biggest cyberextortion attack in history is going to be dwarfed by the next big ransomware attack.
France's carmaker Renault was forced to stop production at a number of sites. In this May 12, 2017 photo, a display panel with an error can be seen at the main railway station in Chemnitz, Germany. Universities in China, Italy and Greece were also hit.