The cyberattack that spread malicious software around the world, shutting down networks at hospitals, banks and government agencies, was thwarted by a young British researcher and an low-priced domain registration, with help from another 20-something security engineer in the U.S.
The Guardian newspaper reported Saturday that the 22-year-old Britain-based researcher, identified online only as MalwareTech, found that the software's spread could be stopped by registering a garbled domain name.
The paper quoted the researcher as saying: "This is not over".
It said the attack will likely take the shape of a phishing email with a malicious attachment or link in it and exploits machines running un-updated versions of Windows XP through to Windows 2008.
It remains unknown who is behind the attack and what their motivation for the attack is.
Friday's attack was the latest in the growing menace of ransomware in which hackers deliver files to computers that automatically encrypt their data, making it unusable until a ransom is paid. It crippled the British health care system for a day, infecting almost 20 percent of its health care groups, forcing medical treatments to be canceled or postponed for thousands of people.
The US government on Saturday issued a technical alert with advice on how to protect against the attacks, asking victims to report any to the Federal Bureau of Investigation or Department of Homeland Security.
It is feared more cases of the "Wannacry" cyber attack will be uncovered in Ireland as businesses re-open tomorrow.
A "patch" is a piece of software created to update a computer program or its supporting data, to fix or improve it.
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Union members at French carmaker Renault say the global cyberattack has forced it to halt production at sites in France in an effort to stop the malware from spreading.
As terrifying as the unprecedented global "ransomware" attack was, cybersecurity experts say it's nothing compared to what might be coming - especially if companies and governments don't make major fixes. Intelligence officials wouldn't comment on the authenticity of the claims.
Europol, the European Union's police agency, said the onslaught was at "an unprecedented level and will require a complex worldwide investigation to identify the culprits".
It said that train services were not disrupted but some electronic boards at stations announcing arrivals and departures had been affected.
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.
Europol's Wainwright said few banks in Europe had been affected, having learned through the "painful experience of being the number one target of cyber crime" the value of having the latest cyber security in place.
It was believed to the biggest attack of its kind ever recorded. Deutsche Bahn said it deployed extra staff to help customers. Omer Fatih Sayan said the country's cyber security center is continuing operations against the malicious software.
National Health Service: At least sixteen NHS organizations have been hit, according to NHS Digital.
Described as the greatest cyber ransom assault, the attack started on Friday affecting state agencies and important companies around the globe including Russian banks, British hospitals in addition to FedEx as well as European vehicle factories.