Information Systems Security Engineer

Leidos is seeking an experienced Information Systems Security Engineer (ISSE) to lead the security architecture, design, and deployment of mission-critical applications across unclassified, classified, and corporate networks. This role is highly dynamic, requiring a security SME who can bridge network boundaries across DTRA, DIA, and corporate infrastructures leveraging AWS multi-region and hybrid cloud environments. The ideal candidate will design robust Cross Domain Solutions (CDS) and ensure compliant application deployments across multiple government and commercial domains. . Key Responsibilities Cross Domain Architecture: Design, integrate, and test Cross Domain Solutions (CDS) allowing secure, policy-compliant data transfers and multi-level data sharing between unclassified and classified environments. AWS Cloud Security: Engineer and maintain secure application architectures within AWS (Commercial, GovCloud, and Secret/Top Secret regions) using cloud-native security tools, IAM policies, and VPC configuration. Multi-Agency Security Integration: Coordinate security compliance and boundary protection architectures across differing DTRA, DIA, and corporate infrastructures. Secure Application Deployment: Oversee the secure deployment and integration of applications across both high-side and low-side systems, ensuring compatibility with both government networks and corporate enterprise baselines. RMF & Compliance Management: Author and maintain System Security Plans (SSPs) and authorization artifacts within eMASS, aligning security controls across NIST 800-53, ICD 503, FedRAMP, and agency-specific overlays. Vulnerability Management: Perform routine system audits, analyze vulnerability scans (e.g., ACAS/Nessus, AWS Security Hub, Prisma Cloud), and guide technical teams through STIG remediation and continuous monitoring. Government Liaison: Serve as the primary security liaison with Authorizing Officials (AOs), ISSOs, and external stakeholders from DTRA, DIA, and corporate leadership to achieve and maintain reciprocity and Authority to Operate (ATO). Required Qualifications U.S. Citizenship is required Candidate must possess an active TS/SCI, or a Top Secret clearance with a current SSBI, and be eligible to obtain a TS/SCI w/ poly level clearance Requires deep understanding of and ability to apply principles, theories, and concepts of technical domain and has broad understanding of other related specialty areas. Typically requires BS degree and 4 – 8 years of prior relevant experience in order to operate within the scope contemplated by the level. Certifications, education and relevant work experience will be considered in lieu of a degree. Cloud Expertise: Deep knowledge of AWS security controls,, Windows/Linux server administration, shared responsibility models, and cloud-native architecture across disparate security classification levels. Agency-Specific Knowledge: Direct experience working within or interfacing with DTRA and DIA networks, security processes, and assessment/authorization lifecycles. Includes experience with VMware, Azure virtual desktop, and Citrix. Experience with container platforms managed via Kubernetes and Docker. CDS/Multi-Level Security: Deep understanding of Cross Domain Solution technologies, data labeling, guard configurations, and secure data transport mechanisms. Hybrid Systems Engineering: Proven ability to securely integrate government mission systems with commercial/corporate infrastructures, maintaining strict data separation. Preferred Qualifications Certifications: Active DoD 8570/8140 IAT/IASAE Level III certification (e.g., CISSP, CASP+). AWS Certified Security - Specialty or AWS Solutions Architect certification is highly preferred. If you're looking for comfort, keep scrolling. At Leidos, we outthink, outbuild, and outpace the status quo — because the mission demands it. We're not hiring followers. We're recruiting the ones who disrupt, provoke, and refuse to fail. Step 10 is ancient history. We're already at step 30 — and moving faster than anyone else dares. Original Posting: July 8, 2026 For U.S. Positions: While subject to change based on business needs, Leidos reasonably anticipates that this job requisition will remain open for at least 3 days with an anticipated close date of no earlier than 3 days after the original posting date as listed above. Pay Range: Pay Range $87,100.00 - $157,450.00 The Leidos pay range for this job level is a general guideline only and not a guarantee of compensation or salary. Additional factors considered in extending an offer include (but are not limited to) responsibilities of the job, education, experience, knowledge, skills, and abilities, as well as internal equity, alignment with market data, applicable bargaining agreement (if any), or other law. Leidos Leidos is an industry and technology leader serving government and commercial customers with smarter, more efficient digital and mission innovations. Headquartered in Reston, Virginia, with 47,000 global employees, Leidos reported annual revenues of approximately $17.2 billion for the fiscal year ended January 2, 2026. For more information, visit Pay and Benefits Pay and benefits are fundamental to any career decision. That's why we craft compensation packages that reflect the importance of the work we do for our customers. Employment benefits include competitive compensation, Health and Wellness programs, Income Protection, Paid Leave and Retirement. More details are available here. Securing Your Data Leidos will never ask you to provide payment-related information at any part of the employment application process. And Leidos will communicate with you only through emails that are sent from a Leidos.com email address. If you receive an email purporting to be from Leidos that asks for payment-related information or any other personal information, please report the email to View email address on click.appcast.io. Commitment and Diversity 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.