Governments and computer experts girded Monday for a possible worsening of the global cyberattack that has hit more than 150 countries, as Microsoft warned against stockpiling vulnerabilities like the one at the heart of the crisis.

Ransomware is a type of wicked and malicious software that takes over the system of a computer.

Writing on the company's website, Microsoft's president and chief legal officer Brad Smith gave a post-mortem of last Friday's "WannaCrypt" cyber-attack, which spread across the world thanks to a database of exploits stolen from the US' National Security Agency (NSA).

He also warned that the attackers could well upgrade the virus and remove the "kill switch" part of the code that stops it from spreading, effectively negating any attempts to stop it from spreading.

"It is important to understand that the way these attacks work means that compromises of machines and networks that have already occurred may not yet have been detected, and that existing infections from the malware can spread within networks", said the U.K.'s National Cyber Security Centre in a statement Sunday.

Managers at many companies and other organizations have not taken steps to put proper cybersecurity systems in place despite talking about their importance, Gazeley said. His move may have saved governments and companies millions of dollars and slowed the outbreak before US -based computers were more widely infected.

Spanish firm Telefonica, French automaker Renault, the USA -based delivery service FedEx and the German railway Deutsche Bahn were among those affected. "We will continue to work with affected (organizations) to confirm this", the agency said.

The ransomware, called WannaCry, locks down files on an infected computer and asks the computer's administrator to pay in order to regain control of them.

The attacks exploit a vulnerability in outdated versions of Microsoft Windows that is particularly problematic for corporations that don't automatically update their systems.

Telecommunications company Telefonica TEF.MC was among many targets in Spain, though it said the attack was limited to some computers on an internal network and had not affected clients or services.

The indiscriminate attack began Friday and struck banks, hospitals and government agencies, exploiting known vulnerabilities in older Microsoft computer operating systems. Machines that contained the patch are much less at risk than those that didn't.

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Experts said Sunday it appeared that the ransomware had made just over $32,000, although they expected that number to pop when people went back into the office Monday. Wainwright said Europol did not know the motive.

The head of Turkey's Information and Communication Technologies Authority or BTK says the nation was among those affected by the ransomware attack.

However, British cybersecurity expert Graham Cluley doesn't want to blame the NSA for the attack.

WannaCry has already caused massive disruption around the globe.

Sixteen National Health Service organizations in the United Kingdom were hit, and some of thosehospitals canceled outpatient appointments and told people to avoid emergency departments if possible.

Reports suggest that over two lakh systems globally could have been infected by the malicious software.

How To Protect Yourself From WannaCry Ransomware? State media reported that digital payment systems at PetroChina gas stations were offline, forcing customers to pay cash.

"We need to keep in mind that this attack was not a sophisticated attack, and people could and would protect themselves by keeping their OS up to date".

Russia's Interior Ministry acknowledged a ransomware attack on its computers.

The 200,000 victims included more than 100,000 organizations, Europol spokesman Jan Op Gen Oorth told The Associated Press.

Dame Fiona and the Care Quality Commission wrote to Mr Hunt to highlight a "lack of understanding of security issues", the newspaper said, and that "the external cyber threat is becoming a bigger consideration". The company did issue a patch for Windows XP, but has otherwise largely stopped issuing updates for the software.