An organization fell victim to a ransomware attack that successfully infected 256 hosts within its network. In the aftermath of this incident, the organization's cybersecurity team must prepare a thorough root cause analysis report. This report aims to identify the primary factor or factors that led to the successful ransomware attack and to develop strategies for preventing similar incidents in the future. In this context, what should the cybersecurity engineer include in the root cause analysis report to demonstrate the underlying cause of the incident?