Final answer:
The best data sources to support an investigation into suspicious activities would be Firewall logs, Employee login history, System performance metrics, and Network traffic logs, which provide a comprehensive view of the network and activities for effective network security management.
Step-by-step explanation:
To support the investigation into the sudden increase in unidentified activities on a technology firm's Security Information and Event Management (SIEM) incident tracking system, an investigator would require access to a combination of data sources that can shed light on the nature of the network activities. The best combination of data sources would be:
Firewall logs, which would help identify unauthorized access attempts or other suspicious activities at the network perimeter.
Employee login history, which could reveal any unusual access patterns or attempts by employees or potential impersonators.
System performance metrics, to determine if the activities have had an impact on the system's operations or if they coincide with performance anomalies.
Network traffic logs, which would provide detailed information about the data being transferred over the network and potentially identify malicious traffic.
Such a multi-faceted approach is crucial for conducting a thorough investigation, identifying the root cause, and improving network security. Historical cases, such as the Target data breach, demonstrate the significance of correctly interpreting security alerts to prevent costly outcomes. The use of a combination of quantitative data, like logs and metrics, is imperative alongside a root cause analysis for a well-informed response to potential security incidents.