The Information System Security Officer (ISSO) serves as a steward of classified and high-side information systems, ensuring security compliance and operational resilience in accordance with DoD and DCSA standards. The role involves executing Risk Management Framework (RMF) activities, pursuing Authorization to Operate (ATO) via eMASS, conducting vulnerability scanning with tools like Nessus, and maintaining compliance with NISP and federal requirements.… Responsibilities include hands-on system administration, security monitoring, patch management, data transfer operations, and collaborative work with industrial security teams to integrate technical and administrative controls. Success requires proven experience processing ATO packages, system administration skills, security compliance knowledge, and the ability to balance rigorous security controls with operational effectiveness.