Your attack surface is the sum total of all attack vectors that can be used against your perimeter defenses. It is simply the amount of information that you are exposing the outside world. The attack surface is the most important thing hackers will need to exploit to break into your network. When attacking targets, professional hackers usually follow the cyber kill chains. Typically, the first step in this process is to survey the target's attack surfaces. This is called advanced reconnaissance. By reducing the attack surface, you can reduce the risk and prevent attacks from ever happening. The cyber kill chain is a method for categorizing and tracking all stages of a cyberattack, from early reconnaissance to the exfiltration data.