What term refers to the total set of penetrations of a boundary surrounding system elements?

The attack surface refers to the total set of penetrable points in a system, where unauthorized users (attackers) can attempt to gain access or exploit vulnerabilities. This concept is crucial in assessing the security posture of applications and systems because it encompasses all potential entry points and interactions that could be exploited by attackers.

By understanding the attack surface, security professionals can identify which components of the system need stronger defenses and monitoring. It involves identifying all the interfaces in an application, such as APIs, user inputs, and network connections, and evaluating the risks associated with each interface. Reducing the attack surface often leads to improved security by minimizing the number of potential vulnerabilities that could be exploited.

The other terms, while related to security, do not encapsulate this concept in the same way. For instance, the security boundary refers to the defined limits of a secured environment, and the risk surface more broadly considers areas of exposure to threats without the specific focus on penetrable points. The vulnerability surface pertains to the areas where known vulnerabilities exist but does not address the total set of exposure points as comprehensively as the attack surface does.