Which incident handling phase involves determining the scope of a security incident?

The phase that involves determining the scope of a security incident is the Detection and Analysis phase. During this stage, security professionals work to identify whether an incident has occurred, assess the nature of the incident, and understand its potential impact. This includes gathering and analyzing data related to the incident, such as logs, alerts, and other indicators of compromise.

In this phase, establishing the scope is crucial as it helps incident responders understand the breadth of the incident, which systems or data may have been affected, and how deeply the intrusion penetrated the organization's defenses. This assessment is fundamental for making informed decisions about how to effectively manage the incident, including containment and recovery efforts.

Other phases, such as Preparation, focus more on establishing policies, procedures, and tools for incident response, rather than on assessing actual incidents. Containment, Eradication, and Recovery deal with responding to incidents that have already been identified, while Post-Incident Activity involves reviewing the incident after response efforts are complete to improve future responses. Thus, the Detection and Analysis phase is specifically where the scope of a security incident is determined, making it the correct choice.