Ransomware is one of the more annoying threats which are currently popular. For the last few years there have been programs which will encrypt your documents folder if you are unfortunate enough to become infected. They then demand that a payment be made in the hopes that a key will be sent which can unlock your files.
Just recently I read an article about a new type of ransomware which isn’t happy with just encrypting your documents. Instead, it forces a system crash and reboot at which point it will encrypt your entire hard drive!
Fortunately, simply keeping your operating system and applications up-to-date with the latest security patches will prevent most of these programs from installing, but the most important protection is simply keeping your files backed up somewhere other than your computer’s hard drive.