What defines a security breach?

A security breach is defined by a situation that involves unauthorized access which compromises the integrity, confidentiality, or availability of information or systems. This definition emphasizes the aspect of unauthorized access, such as hacking, which might allow an attacker to view, steal, or manipulate sensitive data without permission. The incident leads to a failure in the security measures that should protect the information, resulting in potential harm to individuals or organizations.

The other options highlight scenarios that do not align with the concept of a security breach. For instance, an incident with authorized access does not involve any unauthorized entry, thus it does not constitute a breach. Similarly, effective implementation of security policies indicates that systems are well-protected, which is the opposite of what a security breach entails. Lastly, a scheduled security update is a proactive measure intended to prevent vulnerabilities, rather than a breach itself. This reinforces that a security breach is specifically tied to unauthorized actions that damage or threaten the security framework of an organization.