Microsoft Office macros are back as reliable way to spread viruses and malware. This works by inserting a malicious macro into an otherwise normal looking document. This could be a Word document, Excel spreadsheet or PowerPoint presentation.
Take a look at the email we received the other day. I'm sure Bedoes is a fine Georgia restaurant, but they are not immune from hacking and viruses. Neither are any of your typical vendors, so just assume this came from someone you do business with on a regular basis.
The attached spreadsheet looks innocent enough and even pertains to the subject of the message. If you try to open it with a modern version of Excel (Office 2010 of later), you will receive a warning about the macro, but it does not prevent you from running it. If you have certain versions of Office or clones (Open Office, Libre Office, etc), you may not get a warning at all and could be immediately infected.
If you receive an attachment of any type--even from someone you know-- be very, very cautious about opening it. If unsure, it is always best to call the sender to confirm.