Information System Security Engineer; ISSE

Overview

Leidos Undersea Systems Division (USD) is seeking a proactive and experienced Information System Security Engineer (ISSE) to serve as the subject matter expert for critical IT systems at Stennis Space Center, MS. The primary focus of this position is to design, develop, and implement secure information systems. The ISSE collaborates with engineers and developers to integrate robust security measures into systems, ensuring they are resilient against threats and vulnerabilities.

This role requires a deep understanding of security engineering principles and a proactive approach to risk management throughout the system lifecycle. The successful candidate will be a self‑starter, comfortable with extensive travel, and capable of thriving in dynamic and physically demanding environments.

• Perform and review technical security assessments to identify vulnerabilities and ensure compliance with information assurance standards and regulations.
• Validate and verify system security requirements, establish system security designs, and integrate system security capabilities for various environments.
• Build cybersecurity into systems deployed to operational environments, ensuring uniform application of security policies and enterprise solutions.
• Assess and mitigate system security threats and risks throughout the program life cycle, contributing to security planning, assessment, risk analysis, and risk management.
• Apply system security engineering expertise in areas such as system security design, life cycle, risk management, and security testing, using industry system security engineering methodologies.
• Enforce the design and implementation of trusted relationships among external systems and architectures and manage changes to systems while assessing security impact.
• Support security authorization activities in accordance with Government regulations, Department of Defense and NIST Risk Management Framework standards, and customer‑specific information security policies, processes, and procedures.
• Create, manage, and maintain all necessary documentation required to obtain and maintain a system's Authority to Operate (ATO). Ensure all evidence is accurately captured for ATO requests and extensions.
• Identify, track, and manage all configuration changes. Implement and validate system security controls using STIGs and SCAP to ensure compliance.
• Conduct field maintenance and system grooming to ensure optimal performance. Assist with installations and testing as needed.

• BS degree and 8–12 years of prior relevant experience.
• Active TS/SCI clearance.
• Proven experience in a hybrid role combining system administration with information assurance.
• Demonstrated experience as an ISSE/ISSM/ISSO/SCA.
• Experience creating documentation to obtain and maintain an ATO.
• Proficiency with STIGs and SCAP tools for configuration tracking and compliance.
• Deep understanding of the Navy Risk Management Framework process.
• Comfortable working on multiple systems and components simultaneously in various configurations.
• Hold one or more of the following certifications:
  Security+, CISSP, CISM, CAP, ISSEP.
• Ability to work independently with minimal supervision.
• Excellent communication skills, with the ability to translate complex IA concepts for various audiences.
• US citizen.
• Valid US passport and willing to travel extensively.

• Extensive travel up to 12 separate, week‑long trips annually (approximately 6 CONUS and 6 OCONUS).
• Movement around piers, docks, and industrial facility spaces. Ability to climb ladders up to 20 ft.
• Transport or lift objects weighing up to 50 pounds.
• Constant use of hands and fingers to operate tools and computer equipment.
• Move about various work spaces, stoop, kneel, or reach for extended periods.
• Able and willing to work aboard marine vessels of various sizes, which may include overnight stays.

Pay Range: $ – $. Employment benefits include competitive compensation, Health and Wellness programs, Income Protection, Paid Leave and Retirement. For more details, visit

All qualified applicants will receive consideration for employment without regard to sex, race, ethnicity, age, national origin, citizenship, religion, physical or mental disability, medical condition, genetic information, pregnancy, family structure, marital status, ancestry, domestic partner status, sexual orientation, gender identity or expression, veteran or military status, or any other basis prohibited by law. Leidos will also consider for employment qualified applicants with criminal histories consistent with relevant laws.