The malware is installed on the host computer, the user locked out and the data shelved.
"WannaCry" is infecting computers running the older versions of Microsoft Windows operating systems, locking access to files on the computer.
Lawrence Abrams, a New York-based blogger who runs BleepingComputer.com, says many organizations don't install security upgrades because they're anxious about triggering bugs, or they can't afford the downtime.
David Atch, CyberX Labs' vice president for research, said he believes some of the sites he's found are especially vulnerable because utilities tend to run older systems that can't updated or patched. The malware primarily targeted users of Windows XP, which was launched by Microsoft in 2001.
Questions are now being asked about the vulnerabilities caused by reliance of many parts of the NHS on ageing infrastructure and software.
The breach was first reported at Britain's National Health Service.
"We're looking at many decades of building complex systems - one on top of the other - with no effort to go back to fix what we did wrong along the way", said Wendy Nather, principal security strategist at Duo Security, who has worked in security for 22 years. However, there were speculations that some banks in Kerala, Andhra Pradesh had got affected by the cyber attacks.
Criminal hacking groups have repurposed a second classified cyberweapon stolen from United States spies and have made it available on the so-called dark web after the success of the WannaCry attack that swept across the globe on Friday.
Coverage for extortion, business interruption and the cost of outside experts is included under broad cyber policies that many organizations buy, Mr. Reagan said.
The culprit was "ransomware" known as WanaCryptOr 2.0, or WannaCry. Staff said they would continue to monitor and update their systems as a precaution. He noted there was no indication the cyber attack had resulted in widespread disclosure of personal data. Because WannaCry uses an outdated Windows file sharing mechanism to spread across offices and organizations, most home computers are safe.
All-India Bank Officers Confederation Secretary S.K. Srinivas said the auto-shutdown of ATMs would be rectified soon.
"This is hypocritical of the USA, to say the least, because no other country has mounted such wide-ranging, costly and long-term surveillance operations in the history of the internet as the NSA's PRISM and other spy programs".
Sen further added that people need to be careful about emails with unnecessary attachments or links that seem suspicious to avoid being hit by the ransomware threat.
Governments "need to take a different approach and adhere in cyberspace to the same rules applied to weapons in the physical world", Smith says, urging agencies to "consider the damage to civilians that comes from hoarding these vulnerabilities and the use of these exploits".