The biggest cyberattack the world has ever seen is still claiming victims and threatens to create even more havoc on Monday when people return to work. Ransomware is a type of malware that essentially takes over a computer and prevents users from accessing data on it until a ransom is paid, he said.
Wainwright said Europol provided free downloads of decryption programmes for most ransomware.
Friday's global cyber-attack has affected more than 200,000 victims in 150 countries and regions, Europol chief Rob Wainwright said Sunday.
Hospitals, major companies and government offices were among those that were badly affected.
Nonetheless, the experts say such widespread attacks are tough to pull off.
U.S. Treasury Secretary Steven Mnuchin, at a meeting in Italy, said Saturday the attack was a reminder of the importance of cybersecurity. In most cases, they change the wallpaper of the computer and give specific instructions telling the user how to pay to recover their files.
The malware is spread by taking advantage of a Windows vulnerability that Microsoft released a security patch for in March.
Businesses that failed to update Microsoft Windows-based computer systems that were hit by a massive cyber attack over the weekend could be sued over their lax cyber security, but Microsoft Corp itself enjoys strong protection from lawsuits, legal experts said.
But the patches won't do any good for machines that have already been hit.
"We will continue to work with affected (organizations) to confirm this", the agency said. His law firm sued LinkedIn after a 2012 data breach, alleging individuals paid for premium accounts because the company falsely stated it had top-quality cyber security measures. Wainwright said Europol did not know the motive.
Who perpetrated this wave of attacks remains unknown.
Only two health trusts were still "impacted" by the attack on Monday, far fewer than the 47 on Friday, Rudd said.
These hackers "have caused enormous amounts of disruption- probably the biggest ransomware cyberattack in history", said Graham Cluley, a veteran of the anti-virus industry in Oxford, England.
Sixteen National Health Service organizations in the United Kingdom were hit, and some of those hospitals canceled outpatient appointments and told people to avoid emergency departments if possible.
Friday, we saw the NHS was being held to ransom, as hospitals were paralysed by Friday evening as operations were cancelled and GP surgeries were locked out their computer systems also. The company reported that the attack was carried out with the use of ransomware dubbed WannaCry. State media reported that digital payment systems at some gas stations were offline, forcing customers to pay cash.
Major global companies said they also came under attack.
Interior Ministry: The Russian Interior Ministry acknowledged a ransomware attack on its computers, adding that less than 1% of computers were affected.
Malware is a general term that refers to software that's harmful to your computer, said John Villasenor, a professor at the University of California, Los Angeles.
Security experts have warned that another attack is imminent and could be unstoppable.
Security officials in Britain urged organizations to protect themselves by installing the security fixes, running antivirus software and backing up data elsewhere. Here's how to turn automatic updates on. Hackers said they stole the tools from the NSA and dumped them on the internet.