And many computer networks, particularly those in less-developed parts of the world, still use an older version of Microsoft software, Windows XP.
However, the authors of the "WannaCry" ransomware attack told their victims the amount they must pay would double if they did not comply within three days of the original infection - by Monday, in most cases. WannaCry, the virus involved in the current attack, is thought to be based on software developed by the US National Security Agency.
"They're going to turn on their computers in the morning and find out if they were protected or not", said James Barnett, a security expert at Venable and retired Navy rear admiral.
MAKE SAFE AND SECURE BACKUPS Once your files are encrypted, your options are limited. Backups often are also out of date and missing critical information.
A Jakarta hospital said on Sunday that the cyber attack had infected 400 computers, disrupting the registration of patients and finding records. Back up your data on an offline hard drive. 4.
UPDATE AND PATCH YOUR SYSTEMS The latest ransomware was successful because of a confluence of factors.
Among those waking up Monday to a nasty surprise could be government officials, some analysts said. Updating software will take care of some vulnerability.
Wainwright said Europol was working with the Federal Bureau of Investigation in the United States to track down those responsible, saying that more than one person was likely behind it. "I hope that if another attack occurs, the damage will be a lot less".
The computer can be infected by taking advantage of a Windows vulnerability that Microsoft (MSFT, Tech30) released a security patch for in March and computers that hadn't updated were still at risk. "So long as the domain isn't revoked, this particular strain will no longer cause harm, but patch your systems ASAP as they will try again".
Businesses could face legal claims if they failed to deliver services because of the attack, said Edward McAndrew, a data privacy lawyer at Ballard Spahr. This software, which Microsoft released in 2001, was one of the most common operating systems of the 2000s.
Microsoft advises users to avoid clicking on links in or downloading attachments from emails from senders you do not recognise. Radio Slovenia said Saturday the Revoz factory in the southeastern town of Novo Mesto stopped working on Friday evening to stop the malware from spreading. Worms spread easily on a network of computers, especially inside an organisation.
Ransomware is a program that gets into your computer, either by clicking on the wrong thing or downloading the wrong thing, and then it holds something you need to ransom. There's also no guarantee all files will be restored. How much research is being done to stay ahead of criminals?
"If there is a silver lining to it, you're not out a million dollars", he said.
Auto manufacturer Renault said one of its plants, which employs 3,500 people in Douai, northern France, wasn't reopening Monday as technicians dealt with the cyberattack's aftermath.
Edward Snowden concurs: "In light of today's attack, Congress needs to be asking @NSAgov if it knows of any other vulnerabilities in software used in our hospitals", he wrote on Twitter.