role-based access control (RBAC) is the most effective defense against malicious insiders compromising confidential information, as it helps to limit the access of users to the information and resources that are necessary for their roles and responsibilities. RBAC also helps to enforce the principle of least privilege, which reduces the risk of unauthorized or inappropriate access, disclosure, modification, or destruction of information by insiders. RBAC also facilitates the monitoring and auditing of user activities and access rights.

References = Malicious insiders | Cyber.gov.au, Insider Threat Mitigation Guide - CISA, Malicious Insiders: Types, Indicators & Common Techniques - Ekran System