Ransomware 

This is a very good article from Malwarebytes about ransomware, with practical advice about what you can do to prevent your company becoming a victim to this type of threat.  
Our advice on this matter is very simple "its what you do before the disaster that determines how quickly you recover afterwards". Assess which parts of your business are critical to your continued operation, make sure you have daily image backups of all computers and servers that you identified. Copy the backup files to an offsite server to protect from other threats such as fire or theft. We are always available for a free chat to help you make sure your business is protected, its always cheaper to Prevent rather than Cure.