The likelihood of a threat exploiting a vulnerability is primarily determined by its probability of occurrence. This encompasses the frequency with which similar threats have been successful in the past, the sophistication of potential attackers, and the specific characteristics of the vulnerability itself. When assessing risks, understanding how often a similar scenario has been observed provides a basis for estimating how likely a specific threat is to successfully exploit a given vulnerability.
While other factors such as environmental conditions, organizational policies, and user behavior can influence the overall security landscape and contribute indirectly to the risk, they do not directly measure the probability of a specific threat occurring. Environmental conditions might create opportunities for exploitation, organizational policies may dictate how vulnerabilities are managed, and user behavior can either mitigate risk or increase exposure to threats, but none of these factors focus solely on the likelihood aspect in the context of threat exploitation. Therefore, assessing the likelihood of occurrence is crucial in understanding and mitigating risks associated with threats exploiting vulnerabilities.