Unless you've been hiding under a rock since last Friday (12th May 2017 for those skipping through the archives) you can't have missed all the media attention Ransomeware has been getting following a pretty severe hit to the NHS and several other large networks.
Before you all start panicking STOP! The main reason for this happening was severely out of date, in some cases, un-patched operating systems. Windows XP was mentioned many times in reports, this operating system no longer supported by Microsoft is over 17 years old! If you still owned a car (obviously apart from classics) that was 17 years old would you vouch for its reliability?
Ransomware is a type of malicious software that carries out the cryptoviral extortion attack from cryptovirology that blocks access to data until a ransom is paid and displays a message requesting payment to unlock it. Simple ransomware may lock the system in a way which is not difficult for a knowledgeable person to reverse. More advanced malware encrypts the victim's files, making them inaccessible, and demands a ransom payment to decrypt them. The ransomware may also encrypt the computer's Master File Table (MFT) or the entire hard drive. Thus, ransomware is a denial-of-access attack that prevents computer users from accessing files since it is intractable to decrypt the files without the decryption key. Ransomware attacks are typically carried out using a Trojan that has a payload disguised as a legitimate file.