WannaCry: What is ransomware and how to avoid it

Malicious software or "ransomware" has been used in a massive hacking attack, affecting tens of thousands of computers worldwide. Software security companies said a ransomware worm called "WannaCry" infected about 57,000 computer systems in 99 countries on Friday, with Russia, Ukraine, and Taiwan being the top targets. The hack forced British hospitals to turn away patients, affected Spanish companies such as Telefonica, and threw other government agencies and businesses into chaos.