Malicious insider threat is a significant issue for the health-care industry. The purpose of this qualitative single case study was to investigate contractor cybersecurity professionals’ perception of controls used to detect and mitigate malicious privileged user abuse in the DoD’s health-care environment at Network Security System Plus (NSSPlus). The following research questions were addressed in this study: What controls do contractor cybersecurity professionals perceive are required to protect sensitive DoD health-care data against malicious privileged user abuse; What are contractor cybersecurity professionals’ perceptions of the effectiveness of malicious privileged user abuse controls to protect sensitive DoD health-care data; and What other safeguards do contractor cybersecurity professionals perceive are effective in protecting sensitive DoD health-care data against malicious privileged user abuse? Contractor cybersecurity professionals who specialize in insider threat controls at NSSPlus were the population group for this study. Through open, axial, and selective coding, six themes were deduced for this study, which provided a deeper comprehension of the controls required to detect and mitigate malicious privileged user abuse effectively. The implications for practice of this study suggest the DoD health-care environment collaboratively incorporate privileged user administrative, technical, and physical control; enforced controls and used a Defense-in-Depth approach; and invest in emerging proactive and preventive controls, such as user and entity behavior analytics (UEBA), just in time (JIT) privileged account management (PAM), polygraphs, machine learning and Artificial Intelligence (AI).