Let’s imagine that your business has a hidden back door—one that your building manager doesn’t even know exists—and that door leads straight into the heart of your office. By the time someone finds out that door exists, someone could have snuck in to wreak all kinds of havoc, unbeknownst to you. This is what is known as a zero-day threat; it’s a security vulnerability that is being actively exploited in the wild, one that was previously unknown to the vendor and unpatched against, and it’s a serious problem for any SMB.
