Information Systems Security Engineer (ISSE)

Overview LMI is seeking an Information System Security Engineer (ISSE) to design, implement, and validate security controls for Amazon Web Services (AWS) infrastructure and mission applications supporting Department of War mission partners. The ISSE will engineer secure solutions across development, deployment, and operations. This hands-on role focuses on security architecture, hardening, AWS cloud and container security, automation, vulnerability remediation, and technical testing. The ISSE will work with engineers, the Information System Security Manager (ISSM), and the Information System Security Officer (ISSO) to implement controls and provide evidence supporting authorization and continuous monitoring. This remote position requires an active Secret security clearance. Periodic travel may be required for integration, assessments, customer meetings, and access to approved facilities. All classified work must be performed in approved facilities. LMI is a new breed of digital solutions provider dedicated to accelerating government impact with innovation and speed. Investing in technology and prototypes ahead of need, LMI brings commercial-grade platforms and mission-ready AI to federal agencies at commercial speed. Leveraging our mission-ready technology and solutions, proven expertise in federal deployment, and strategic relationships, we enhance outcomes for the government efficiently and effectively. With a focus on agility and collaboration, LMI serves the defense, space, healthcare, and energy sectors, helping agencies navigate complexity and outpace change. Headquartered in Tysons, Virginia, LMI is committed to delivering impactful results that strengthen missions and drive lasting value. Responsibilities Translate mission needs and security requirements into system architectures, control implementations, secure configurations, and testable acceptance criteria. Perform threat modeling and security design reviews; identify trust boundaries, attack surfaces, data flows, dependencies, and technical risks before deployment. Engineer and implement security controls for AWS infrastructure, Linux systems, containers, Kubernetes, application interfaces, and supporting services in coordination with system owners. Configure and validate identity and access controls, least-privilege permissions, network segmentation, encryption, certificates, secrets management, audit logging, and security monitoring. Apply Defense Information Systems Agency Security Technical Implementation Guides (STIGs) and approved hardening baselines; test changes for security effectiveness and mission impact. Integrate security scanning and checks into continuous integration and continuous delivery pipelines, including code, dependency, container-image, secrets, and infrastructure-configuration checks. Use scripting, infrastructure as code, and configuration automation to deploy repeatable security controls, detect configuration drift, and collect technical evidence. Analyze vulnerability findings, validate applicability, implement fixes, and retest remediation; propose compensating controls for authorized review when immediate correction is not feasible. Develop and execute security verification tests, support authorized assessments, and troubleshoot issues involving application, network, cloud, identity, and container security controls. Produce security diagrams, configuration baselines, control implementation details, and test evidence supporting Risk Management Framework (RMF) activities and Authority to Operate (ATO) packages. Coordinate technical remediation and closure evidence with the ISSO and ISSM; document residual risks and recommendations for government risk decisions without independently accepting risk. Assess proposed system changes, maintain engineering documentation and runbooks, and support incident investigation, recovery, and corrective actions with responsible operations teams. Qualifications Required Qualifications: Active Secret security clearance, with the ability to obtain and maintain Top Secret if required by the assignment. Minimum of five years of relevant experience in systems security engineering, cybersecurity engineering, cloud security, secure platform engineering, or a related technical field. Hands-on experience implementing, troubleshooting, and validating security controls. Policy review or compliance documentation experience alone does not satisfy this requirement. Experience engineering or securing Department of Defense (DoD) information systems, including systems operating on or connected to the Department of Defense Information Network (DODIN). Demonstrated hands-on professional experience implementing, securing, operating, and troubleshooting AWS workloads. Candidates must be able to describe AWS environments they supported, security controls they personally implemented, and remediation they validated. AWS certification or coursework alone, or experience limited to other cloud providers, does not satisfy this requirement. Practical experience with AWS Identity and Access Management (IAM), Amazon Virtual Private Cloud (VPC), security groups, compute and storage security, encryption, and AWS logging and monitoring, including AWS CloudTrail and Amazon CloudWatch. Experience hardening and troubleshooting Linux systems and containerized workloads, with working knowledge of Kubernetes security controls. Experience using scripting, infrastructure as code, or configuration-management tools to automate security tasks, and working with source control and software delivery pipelines. Working knowledge of TCP/IP networking, routing, firewalls, network segmentation, secure application connectivity, certificates, encryption, and identity and access management. Experience applying RMF requirements, NIST SP 800-53 controls, STIGs, vulnerability scanning, and remediation practices to technical implementations and authorization ev