**Mantech** seeks a motivated, career-driven, and customer-focused **Information System Security Officer (ISSO)** to join our team in **Annapolis Junction, MD** . This position plays a critical role in supporting enterprise infrastructure capabilities for a global, mission-focused workforce. Supporting high-visibility Enterprise Infrastructure Services (EIS) organization, responsible for the delivery and security of MPO’s Enterprise Information Technology (EIT)—the foundation for enterprise-wide services. As an ISSO, you will work alongside customers, Integrated Product Teams (IPTs), and vendors to support the implementation and compliance of advanced EIT capabilities through Data Center & Compute Services. **Responsibilities include, but are not limited to:** + Update and maintain hardware and software inventory records, including associated change logs + Support and coordinate Secure the Enterprise (STE) and Secure the Network (STN) activities + Review and address Xacta notices and ensure compliance documentation is accurate and current + Track, review, and resolve POAMs (Plan of Action and Milestones) related to IAVA/IAVAx findings + Develop and maintain System Security Plans (SSPs) for both new and existing systems + Analyze vulnerability scan results and collaborate with system owners to implement remediation + Leverage sponsor tools such as Gatekeeper, Xacta, SEAR, and LatteArt in daily operations **Minimum Qualifications:** + Bachelor’s degree with 10+ years of relevant ISSO experience OR 4 additional years of related experience as an ISSO might be substituted for a degree + Experience with Xacta, LatteArt and other sponsor tools + Experience managing POAMs, performing audit log reviews, and maintaining secure system inventories + IAM I certification (DoD 8140 required upon start of employment. Acceptable certifications include CAP/CND/Cloud+/GSLC/Security + CE/HCISSP/CASP+CE/CISM/CISSP/ or CCISO) + Experience reviewing, preparing, and updating ATO packages in accordance with NIST Risk Management Framework and customer policy, procedures, and guidelines **Preferred Qualifications:** + Knowledge of STE and STN processes and coordination + Experience with Gatekeeper, SEAR, SCANBOY + Demonstrated experience in SSP development and incident response management **Clearance Requirements** + Must possess and maintain a current/active TS/SCI clearance with Polygraph **Physical Requirements:** + Must be able to remain in a stationary position 50% of the time + Occasionally moves about inside the office to access file cabinets, office machinery, etc. + Frequently communicates with co-workers, management, and customers, including delivering presentations. Must be able to exchange accurate information in these situations ManTech International Corporation, as well as its subsidiaries proactively fulfills its role as an equal opportunity employer. We do not discriminate against any employee or applicant for employment. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, disability, or status as a protected veteran. If you are a qualified individual with a disability and require a reasonable accommodation to apply for a position with ManTech through its online applicant system, please email us at careers@mantech.com and provide your name and contact information.