The Senior ISSO collaborates with the ISSM to steward classified and high-side information systems, ensuring a resilient security posture aligned with DoD and DCSA standards. Responsibilities include executing Risk Management Framework (RMF) activities, pursuing Authorization to Operate (ATO) via eMASS, conducting vulnerability scanning (Nessus), performing security assessments, and maintaining compliance with NISP, DoD, and DCSA requirements.… The role combines hands-on system administration (patching, backups, configuration), compliance documentation and monitoring, and liaison work with DCSA ISPPs and internal security teams. Success requires deep expertise in security compliance, secure operations, system administration basics, and the ability to balance rigorous controls with operational effectiveness.