SMX is seeking a highly experienced **Information System Security Officer (ISSO) – Sr** to support a mission-critical federal program in Washington, DC. This individual will serve as a senior cybersecurity professional and trusted advisor responsible for ensuring the security, compliance, and operational integrity of enterprise information systems supporting critical mission functions. The selected candidate will function as the principal advisor to System Owners (SOs), Business Process Owners, Information System Security Managers (ISSMs), and cybersecurity leadership on all matters involving information system security. This role requires extensive experience implementing and maintaining security controls, supporting Risk Management Framework (RMF) activities, leading authorization efforts, and providing technical guidance across multiple systems and projects. The ISSO – Sr will serve as a technical expert responsible for evaluating security posture, mitigating risk, recommending se...