Information Systems Security Engineer - General

Pegasi Defense is seeking an experienced Information Systems Security Engineer (ISSE) to support the security, operations, maintenance, and continuous improvement of mission-critical enterprise information systems within a Department of Defense (DoD) environment.

The ISSE will be responsible for engineering, implementing, assessing, and maintaining cybersecurity controls to ensure enterprise systems remain secure, compliant, and operationally effective. This position will focus on security engineering, vulnerability management, Risk Management Framework (RMF) compliance, continuous monitoring, security assessments, and maintaining the systems' Authority to Operate (ATO).

The ideal candidate will have strong experience securing complex enterprise applications and infrastructure, identifying and remediating cybersecurity vulnerabilities, and supporting security authorization activities within highly regulated federal environments.

Key Responsibilities

Security Engineering & System Protection • Design, implement, maintain, and enhance security controls across enterprise applications, operating systems, databases, networks, and supporting Infrastructure. • Evaluate system architectures, configurations, and technical designs to identify security risks and recommend mitigation strategies. • Implement and validate secure system configurations in accordance with DoD cybersecurity standards and established security baselines. • Collaborate with software engineers, DevSecOps engineers, system administrators, and database administrators to integrate security throughout the system lifecycle. • Support secure authentication, authorization, access management, encryption, certificate management, and data protection mechanisms. • Conduct security impact analyses for proposed system changes, upgrades, patches, and infrastructure modifications. • Develop and maintain security engineering documentation, technical procedures, and system security configurations. • Support system hardening and security improvements while minimizing disruption to production operations.

Risk Management Framework (RMF) & Authorization • Support the implementation and maintenance of cybersecurity controls in accordance with the DoD Risk Management Framework (RMF), NIST SP 800-53, and applicable federal security requirements. • Develop, review, and maintain RMF authorization documentation, including System Security Plans (SSPs), Security Assessment Reports (SARs), Plans of Action and Milestones (POA&Ms), and supporting artifacts. • Support initial authorization, ATO renewals, ongoing authorization, and continuous monitoring activities. • Assess the implementation and effectiveness of security controls and document supporting evidence. • Coordinate with Information System Security Officers (ISSOs), Information System Security Managers (ISSMs), Security Control Assessors (SCAs), and Authorizing Official representatives. • Identify security control deficiencies and recommend corrective actions to reduce risk. • Support cybersecurity inspections, assessments, audits, and authorization reviews. • Maintain accurate security documentation and ensure system changes are appropriately reflected in authorization artifacts.

Vulnerability Management & Security Compliance • Conduct vulnerability assessments and analyze findings using approved security scanning and assessment tools. • Support vulnerability management activities using ACAS/Nessus, Security Content Automation Protocol (SCAP) tools, and other approved technologies. • Evaluate vulnerability findings, determine potential mission impact, and recommend appropriate remediation actions. • Implement, validate, and maintain compliance with Defense Information Systems Agency (DISA) Security Technical Implementation Guides (STIGs) and Security Requirements Guides (SRGs). • Coordinate vulnerability remediation with engineering, infrastructure, database, and application support teams. • Track vulnerabilities, remediation progress, risk acceptance decisions, and POA&M activities. • Perform security configuration reviews, compliance assessments, and technical validation of remediation efforts. • Support the evaluation and mitigation of emerging cybersecurity threats affecting enterprise systems.

Continuous Monitoring & Security Operations • Support continuous monitoring of enterprise systems to identify vulnerabilities, configuration deviations, and potential security risks. • Review security logs, audit records, vulnerability reports, and monitoring alerts to identify potential security issues. • Collaborate with cybersecurity operations teams to investigate security events and support incident response activities. • Evaluate security impacts associated with software releases, infrastructure changes, operating system updates, and application deployments. • Support patch management and security remediation activities across production and nonproduction environments. • Develop and maintain security metrics, compliance reports, and risk assessments. • Identify opportunities to improve security monitoring, automated compliance validation, and vulnerability management processes. • Support security-related root cause analysis and corrective action planning.

Infrastructure & Application Security • Assess and secure enterprise Linux environments, particularly Red Hat Enterprise Linux (RHEL), and other supported operating systems. • Evaluate security configurations for application servers, databases, middleware, and supporting infrastructure. • Support database security assessments, including Oracle database security configurations, access controls, and vulnerability remediation. • Assess application security controls, APIs, authentication mechanisms, and data protection requirements. • Support secure configuration and vulnerability management for virtualized, containerized, or cloud-based infrastructure where applicable. • Evaluate network security controls, firewall configurations, ports, protocols, and system connectivity. • Support Public Key Infrastructure (PKI), CAC/PIV authentication, and identity and access management requirements. • Collaborate with development and DevSecOps teams to integrate security scanning, secure coding practices, and automated compliance checks into CI/CD pipelines.

Collaboration & Continuous Improvement • Participate in technical reviews, change control activities, security assessments, and operational planning meetings. • Collaborate with government stakeholders, engineering teams, cybersecurity personnel, and system administrators to resolve security-related issues. • Provide cybersecurity engineering guidance throughout the software development and system maintenance lifecycle. • Identify opportunities to strengthen system security, reduce operational risk, and improve compliance processes. • Support modernization initiatives by evaluating security implications of new technologies, architectures, and infrastructure changes. • Communicate cybersecurity risks, technical findings, and remediation recommendations to technical and nontechnical stakeholders.

Required Qualifications • Bachelor's degree in Cybersecurity, Computer Science, Information Technology, Engineering, or a related technical field. Equivalent relevant experience may be considered. • 5+ years of experience in information systems security engineering, cybersecurity engineering, information assurance, or related technical roles. • Experience supporting cybersecurity activities for federal government, DoD, or similarly regulated enterprise information systems. • Hands-on experience implementing, assessing, and maintaining security controls in accordance with NIST SP 800-53. • Strong knowledge of the DoD Risk Management Framework (RMF), security authorization processes, and ATO requirements. • Experience developing or maintaining RMF documentation, including SSPs, POA&Ms, security control assessments, and continuous monitoring artifacts. • Experience performing vulnerability assessments and managing remediation activities using ACAS/Nessus or comparable security tools. • Knowledge of DISA STIGs, SRGs, secure configuration baselines, and system hardening practices. • Experience securing and assessing Linux operating systems, particularly Red Hat Enterprise Linux (RHEL). • Understanding of enterprise networking concepts, including TCP/IP, DNS, firewalls, ports, protocols, and secure communications. • Familiarity with enterprise applications, databases, authentication technologies, and supporting infrastructure. • Experience evaluating system security configurations, identifying risks, and recommending technical remediation strategies. • Understanding of vulnerability management, patch management, security monitoring, and incident response processes. • Strong analytical, troubleshooting, documentation, and communication skills. • Ability to work effectively with software engineers, DevSecOps engineers, system administrators, and cybersecurity teams.

Preferred Qualifications • Previous experience supporting mission-critical DoD or federal government enterprise information systems. • Experience supporting high-availability production systems and complex enterprise applications. • Experience with Oracle database security, database STIGs, and secure database configuration. • Experience with RMF management and authorization platforms such as eMASS. • Experience with ACAS, Nessus, SCAP Compliance Checker, STIG Viewer, and other DoD cybersecurity assessment tools. • Familiarity with enterprise security monitoring and logging platforms such as Splunk, Elastic, or comparable SIEM technologies. • Experience with application security testing tools such as Fortify, SonarQube, Checkmarx, or comparable technologies. • Experience assessing containerized environments using Docker, Kubernetes, or OpenShift. • Familiarity with AWS GovCloud, Azure Government, or other government-authorized cloud environments. • Experience supporting secure CI/CD pipelines and DevSecOps security integration. • Knowledge of identity and access management, PKI, CAC/PIV authentication, and certificate management. • Experience supporting vulnerability remediation for legacy enterprise applications and infrastructure. • Familiarity with security architecture reviews, threat modeling, and system security impact assessments. • Experience with automated compliance monitoring, security scripting, and configuration management.

Relevant certifications such as: • CompTIA Security+ • Certified Information Systems Security Professional (CISSP) • Certified Information Security Manager (CISM) • Certified Cloud Security Professional (CCSP) • GIAC Security Essentials (GSEC) • GIAC Certified Incident Handler (GCIH) • Red Hat Certified System Administrator (RHCSA)

Security Requirements • Must be a U.S. citizen. • Must possess or be eligible to obtain the security clearance required for the position. • Must meet applicable DoD 8140 cybersecurity workforce qualification requirements. • Must comply with all applicable government security, access control, and information protection requirements.