Your network is 100 times more likely to be attacked with a known exploit than an unknown one. And the reason behind this is simple: There are so many known exploits and the complexity of networks is so great that the chances are good that one of these known vulnerabilities are present and will allow an attacker access to your data.

The number of networks worldwide is so great and the number of new, as of yet undocumented and thus unknown exploits so small that your chances of being attacked with one is nearly zero – unless you have network assets of truly great value, or you are a particularly interesting target.

If you don’t attract the attention of a dedicated, well financed attack, then your primary concern must be to eliminate your known vulnerabilities so that a quick look would not reveal an easy entry.