While Microsoft had previously released patches for the NSA exploits that WanaCrypt targets, it's taken the rare step of releasing patches for operating systems not now in mainstream or extended support. It was benign because it contained a flaw that prevented it from taking over computers and demanding ransom to unlock files but other more malicious ones will likely pop up.
When the National Security Agency lost control of the software behind the WannaCry cyberattack, it was like "the US military having some of its Tomahawk missiles stolen", Microsoft President Brad Smith says, in a message about the malicious software that has created havoc on computer networks in more than 150 countries since Friday.
But as Asia woke up to the working week on Monday, leading Chinese security-software provider Qihoo 360 said "hundreds of thousands" of computers in the country were hit at almost 30,000 institutions including government agencies.
Hitachi: The Japanese electronics firm said Monday that its computer systems have been experiencing problems since the weekend, including not being able to send and receive emails or open attached files.
In a blog post Sunday, Brad Smith, Microsoft president and chief legal officer, said that the USA espionage agency authored the software that was eventually stolen and made its way into the hands of hackers who drew from it in the assault that has disrupted computers in at least 150 countries.
The virus spread quickly because 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. "We expect that most of these "government-grade" exploits to make it to the public domain and get merged into commercial-grade malware, as it has happened in the past".
"An equivalent scenario with conventional weapons would be the United States military having some of its Tomahawk missiles stolen", Smith wrote.
She said the attack had not been focused on the NHS but was part of a wide global issue, and said the government had invested 2 billion pounds in cyber security. "This most recent attack represents a completely unintended but disconcerting link between the two most serious forms of cybersecurity threats in the world today - nation-state action and organized criminal action", he added.
Experts think it unlikely to have been one person, with criminally minded cyber crime syndicates nowadays going underground and using ever more sophisticated encryption to hide their activities.
The ransomware is so effective because once one PC is infected, it will scan the entire internal network and infect other vulnerable devices, with those running unsupported Microsoft operating systems such as Windows XP bearing the brunt of the attacks.
European governments and companies appeared early Monday to have avoided further fallout from a crippling global cyberattack, the police agency Europol said.
Department of Homeland Security officials told Fox News on Monday that a "limited number" of US companies were hit by the "WannaCry" malicious software over the weekend.
"But as a whole it is worrying, there's nothing good about it, it is a source of concern".
Putin said Russian Federation was not behind the attack. Security agencies in affected countries were racing to find out.
Carmaker Renault said one of its French plants, which employs 3,500 people, wasn't reopening Monday as a "preventative step" while technicians deal with the aftermath of the attack. Europol said Monday that "very few" people have paid the ransom, and security company Bitdefender said the attack has raised just over $51,000.