Almost everyone in the world has an email account. Emailing has been so efficient and time-saving when contacting individuals. Since emailing has been so widespread, it is also easy for attackers to compromise an account and send out fake emails with malicious attachments. What does this mean exactly?
Well, lets say Joe has a friend named Matt, and from time to time they email eachother. Joe always opens up Matt's emails because he knows who he is and trusts him. Let's say that Matt's email account gets compromised and breached. All of the contacts in his address book will get a fake email that is sent from Matt. Given that Matt's contacts know who he is, will highly likely click on the email and if there is an attachment, you can bet that the attachment will be open or even downloaded. This attachment could pose as a PDF, Word Document, or even an Excel Spreadsheet, with a common name that makes you want to open it, and is most likely carrying a virus behind it. This virus could either spread through your computer making most or all programs unusable, or even lock down all document,s photos, music, videos, etc where you have to pay a Ransom to unlock. This malicious virus is called, "Ransomware."
So how can typical users protect themselves? The key to protecting yourself is to be keen and cautious when opening attachments in an email, even if it is from a trustworthy person. The chances are very slim that your Anti-virus will pick up the virus and quarantine it. In a home enviroment, the virus may not spread through your network unlike a corporate environment. In this case, since data is shared among several computers, the virus can spread throgu hall the computers making its way to the main computer, which is the Server.