Which data source should be investigated first when there is a spike in alerts from a SIEM system?

When there is a spike in alerts from a Security Information and Event Management (SIEM) system, log data should be the primary focus for investigation. This is because log data contains the raw details about security events and activities occurring on the network, providing crucial insights into what may be triggering the alerts.

Analyzing log data can help identify patterns, unusual access attempts, or specific actions taken by users or systems around the time of the alert spike. By correlating this log data with the alerts generated, an investigator can determine whether the alerts are indicative of a genuine security threat or if they are false positives resulting from normal operational activities or misconfigurations.

The other data sources may have their place in a comprehensive investigation, but they do not provide as immediate or direct insight into the events that have led to the alerts. For instance, user activity logs can help understand user behavior, but without the context provided by broader log data, their utility may be limited. Similarly, network configurations and incident reports could contribute to the investigation but may not directly explain the immediate cause of the alert spike. Thus, focusing on log data is critical for understanding and responding effectively to the situation.