Ransomware - cyber security and practical tips

WannaCry is the computer malware "worm" that has been infecting computer business systems around the world in the last few days. It reportedly attacks a vulnerability in Microsoft Windows operating systems and locks users out of their own computer systems, demanding a ransom of about $300. Hence the name - "ransomware."

But the $300 ransom is the least of the troubles caused by the attack. The scope for business interruption is huge - with businesses unable to access their data, unable to order stock or send packages, unable to provide services and having to turn customers away.

High profile victims thus far include Britain's National Health Service, French car manufacturer, Renault, and Spanish telecommunications company, Telefónica.