The industrial attack surface is a crucial component in gaining visibility of the various ways unauthorized or malicious access could be fostered in industrial networks with types of attack surfaces. This chapter goes over a few different types or categories of attack surfaces and then transitions into how to measure the size of an attack surface in terms of metrics, how to map out that surface, and finally concludes with strategies for reducing the size of the attack surface. It helps to counter various attack vectors and provides solutions to the prevention for these vectors along with logical and physical access-related attacks. This chapter will extend to address common attack techniques and ways to manipulate the attack surface. This will help readers to understand the weaknesses and entry points used by unauthorized or malicious actors to attack industrial automation systems.