**ManTech** seeks a motivated, career and customer-oriented **Senior Information System Security Officer (ISSO)** to join our team in **Chantilly, VA.** This is an **onsite** position. **Responsibilities include but are not limited to:** + Create and maintain existing information system security documentation, including SSP, SCTM, and Risk Management Framework (RMF) Body of Evidence + Prepare system documentation for assessment in accordance with RMF and NIST Special Publications (800-37, 800-53 and others); identify deficiencies and provide recommendations for solutions; track findings with Plan of Action and Milestones (POA&M) through mitigation and/or risk acceptance + Ensure the appropriate operational security posture is maintained for assigned information systems + Work in close collaboration with the Information System Security Manager (ISSM), the Chief Information Security Officer (CISO) staff, and the Information System Owner (ISO) + Conduct periodic and continuous monitoring of the system to ensure compliance with the authorization package + Work with the Cyber Security team to perform basic system administration and maintain various Cyber Security tools, including audit collection and reporting systems, vulnerability management programs, and other continuous monitoring capabilities + Participate in the change management process, including reviewing Change Requests and assisting in the assessment of security impact of proposed changes + Conduct daily, weekly, and monthly audit review and management of the audit collection system for assigned systems, boundaries, and components + Work on project teams responsible for engineering and packaging releases to integrate within the customer's production IT environment **Minimum Qualifications:** + Bachelor’s degree (preferably in IT, Cyber Security, Computer Science, Information Systems Management, Engineering, or similar field of study) and 4+ years’ experience with information networks and related security concerns; or a Master's degree with 2+ years’ experience may be accepted in lieu of degree + DoD 8570.1 / DoD 8140.01 certification (IAT Level II) + Strong background and extensive experience with RMF, ICD 503, NIST SP800-53, JSIG or DJSIG + Knowledge of current authorization practices, particularly within the DoD **Preferred Qualifications:** + Experience with security efforts related to modern Windows, Cloud computing, Linux, UNIX, Cisco, SQL or Oracle databases, and virtual computing. + Experience implementing and using various Cyber Security tools including vulnerability assessment, patch management, audit collection, audit review, audit management, and end point protection **Clearance Requirements:** + US Citizenship required, and active TS clearance adjudicated within the last 6 years. + Candidate must be open to a polygraph if selected by the customer **Physical Requirements:** + Must be able to remain in a stationary position 50%.Needs to occasionally move about inside the office to access file cabinets, office machinery, etc. + Frequently communicates with co-workers, management, and customers, which may involve 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.