Senior Cybersecurity Engineer / Information System Security Engineer (ISSE)

Seneca Holdings•Remote, MO

About The Position

Great Waters Federal, part of the Seneca Nation Group portfolio, is seeking a highly skilled Senior Cybersecurity Engineer / Information System Security Engineer (ISSE) to support cybersecurity engineering, security operations, vulnerability management, and continuous monitoring for Department of Defense information systems. The role requires at least 10 years of relevant experience and hands-on expertise in vulnerability assessment and remediation, security configuration management, system hardening, endpoint protection, and enterprise systems administration. The engineer independently identifies, assesses, mitigates, and remediates security vulnerabilities while maintaining compliance with applicable DoD cybersecurity requirements, NIST standards, and organizational security policies. The position collaborates with ISSMs, ISSOs, system administrators, network engineers, and other technical stakeholders to maintain the security and operational readiness of mission-critical information systems. Work includes RMF authorization and continuous monitoring, vulnerability scanning and remediation, DISA STIG compliance, HBSS and endpoint security administration, Windows Server and RHEL administration, configuration management, and AWS cloud security. Great Waters Federal describes a collaborative work environment and offers competitive pay, benefits and perks, flexible work-life balance, professional development opportunities, and performance and recognition programs. Full-time employees who regularly work at least 30 hours per week are eligible for benefits and paid leave programs.

Requirements

At least 10 years of relevant professional experience in cybersecurity engineering, information assurance, vulnerability management, or enterprise security operations.
Experience supporting DoD, federal government, or similarly regulated enterprise environments.
Hands-on experience conducting vulnerability assessments, implementing security controls, and remediating technical security findings.
Experience administering, configuring, and securing enterprise Windows and Linux systems.
Experience supporting RMF compliance, continuous monitoring, and security authorization activities.
Strong understanding of enterprise infrastructure, operating system security, endpoint protection, and vulnerability management principles.
Current CompTIA Security+ certification.
Current AWS certification, such as AWS Certified Solutions Architect, AWS Certified SysOps Administrator, AWS Certified Security – Specialty, or another relevant AWS certification.
Must meet applicable DoD 8140 qualification requirements for the position’s designated cybersecurity work role and proficiency level, as established by contractual and governing DoD requirements.
Top Secret security clearance required for full performance. Candidates with an active Secret clearance may be considered if eligible and willing to undergo the Top Secret investigation and adjudication process.
Eligible candidates holding a Secret clearance may be sponsored by the employer for a Top Secret clearance upgrade, subject to government and contractual approval.

Nice To Haves

Practical experience with NIST RMF, NIST SP 800-53, NIST SP 800-137, configuration management, and security baseline enforcement.
Experience with DISA STIG and SRG implementation, eSTIG assessment tools, SCAP compliance scanning, and STIG remediation and validation.
Experience with Tenable Security Center and installation, configuration, and administration of Tenable Nessus scanners.
Experience with vulnerability identification, prioritization, mitigation, and remediation.
Experience administering and managing HBSS.
Experience administering RHEL and Microsoft Windows Server, including operating system patching and security hardening.
Experience with enterprise endpoint security management and Trellix/McAfee ePO.
Experience automating system configuration, compliance assessments, or remediation using Ansible, PowerShell, Bash, or similar technologies.
Experience with AWS security services, cloud infrastructure security, and federal cloud compliance requirements.
Experience developing vulnerability metrics, compliance dashboards, and technical security reports.
Previous experience as an ISSE in a DoD environment.
Experience supporting RMF authorization packages and ATO activities.
Familiarity with DoD cybersecurity policies, security control assessment procedures, and continuous monitoring requirements.
Experience supporting complex, mission-critical enterprise information systems.
Familiarity with enterprise networking, firewall configurations, and network security principles.
Additional professional certifications such as CISSP, CompTIA SecurityX, CySA+, RHCSA, or AWS Certified Security – Specialty.

Responsibilities

Implement and maintain technical security controls in accordance with the NIST RMF and NIST SP 800-53.
Support Information Security Continuous Monitoring activities in accordance with NIST SP 800-137.
Provide technical engineering support throughout the RMF authorization lifecycle, assess security control effectiveness, and identify compliance deficiencies.
Develop and implement corrective actions for security control weaknesses.
Support development and maintenance of System Security Plans, security control implementation statements, assessment evidence, and POA&Ms.
Evaluate proposed system changes for cybersecurity impact and maintain approved security configuration baselines.
Provide technical evidence and remediation support for ATO activities and collaborate with ISSOs and ISSMs on continuous compliance.
Install, configure, administer, maintain, and troubleshoot Tenable Nessus scanners and Tenable Security Center, including scanner integration, repositories, policies, credentials, and reporting.
Conduct authenticated and unauthenticated vulnerability assessments; configure automated scanning schedules and policies; analyze findings; and prioritize remediation by severity, exploitability, and operational impact.
Develop and implement vulnerability mitigation and remediation strategies and coordinate resolution with system administrators, engineers, and system owners.
Perform follow-up vulnerability scans to validate remediation; maintain vulnerability tracking records; and produce reports on findings, remediation status, and residual risk.
Support vulnerability management for Windows Server, RHEL, and AWS environments.
Implement DISA STIGs and SRGs; conduct automated and manual compliance assessments using eSTIG tools, SCAP utilities, and approved assessment tools; and remediate findings.
Develop and maintain secure configuration baselines, investigate configuration deviations, document findings and approved deviations, and validate hardening through scans and manual verification.
Support cybersecurity inspections, audits, and continuous monitoring, and maintain compliance with applicable DoD configuration standards.
Administer, configure, maintain, and troubleshoot HBSS and applicable successor endpoint security technologies, including Trellix/McAfee ePO as applicable.
Manage endpoint security policies, agent deployments, software updates, system health, and endpoint alerts; resolve agent communication, policy enforcement, and compliance issues.
Support endpoint security infrastructure upgrades and configuration changes, and ensure endpoint protection configurations meet DoD requirements.
Administer, configure, secure, and troubleshoot RHEL and Microsoft Windows Server systems, including installation, configuration, patching, hardening, and maintenance.
Maintain approved system baselines, conduct security impact assessments for system and infrastructure changes, and support configuration management and change control.
Identify and resolve operating system vulnerabilities, misconfigurations, and security weaknesses; maintain technical documentation, configuration records, and standard operating procedures.
Collaborate with infrastructure engineering teams to support secure deployment and reliable system operation while maintaining compliance with organizational and DoD requirements.
Support cybersecurity engineering and compliance activities in AWS; implement secure configurations and support cloud vulnerability management, IAM, security monitoring, and configuration assessments.
Identify and remediate cloud security misconfigurations, support security integration between on-premises and cloud-hosted systems, and apply AWS security best practices to protect resources, workloads, and data.