I know that it is sort of a “sky is falling”, FUD (Fear, Uncertainty, and Doubt) sort of statement, but the threat from inside your network is significant. While you focus on keeping unauthorized users out, locking down your network perimeter, detecting and blocking incoming malware, etc., your authorized users may be busy at work pushing the boundaries of their access and poking your internal security measures for holes. Then there are those users who are authorized access and unwittingly expose sensitive data, such as placing it unprotected on a USB thumb drive which they subsequently misplace while stopping for a cup of coffee. There are a number of ways- both intentional, and accidental- that your users may pose a bigger threat to your network security than all of the bad, nasty external forces seeking to compromise your systems. Check out How dangerous user behavior puts networks at risk to read the whole article and hopefully pick up some tips you can use to protect your network from the inside as well.