One of these critical components is an understanding of the industrial attack surface that enables the detection of unauthorized or malicious access within industrial networks. This chapter delves into different attack surface categories and how to measure attack surface metrics and provides mapping and guidance on how to reduce the attack surface. It also deals with various attack vectors (and prevention systems for that) and access attacks, namely logical and physical access. The chapter also explores typical attack scenarios and presents best practices for mitigating the attack surface. This book will help to uncover the major security gaps in a given industrial automation system and show what attackers could potentially exploit to infiltrate other parts of the network.