Which of the following defines a threat in security terms?

In security terms, a threat is identified as a potential harmful incident that could exploit a vulnerability within a system, leading to negative consequences such as data loss, damage to assets, or disruption of services. This definition emphasizes the nature of a threat as something that has the potential to cause harm, rather than being an existing event or a measure taken to secure an environment.

Understanding that a threat is about potentiality helps organizations focus on risk management, whereby they assess and prioritize vulnerabilities based on the threats that are likely to exploit them. This allows for the creation of strategic defenses against identified threats, and informs the development of security policies and practices that mitigate risks.

The other options describe concepts that do not align with the nature of what constitutes a threat. A proactive measure for defense refers to strategies and tools that are implemented to prevent incidents from occurring. An established security protocol is about protocols and standards already in place to secure systems. A reactive response to security breaches indicates a measure taken after an incident has already occurred, which is contrary to the proactive nature of threat identification and management.