Senior Information Systems Security Engineer

Join Amentum as a Senior Information Systems Security Engineer on site in Warrenton, VA. This role centers on leading Trellix ePO and ACAS/Nessus security tooling, designing enterprise security controls, and guiding secure-by-design practices across the software development lifecycle to protect mission-critical assets. The position offers a salary range of USD 165,000 to 185,000 per year, a comprehensive benefits package, and a collaborative culture focused on engineering excellence and resilient systems.

Benefits

• 401(k)
• 401(k) matching
• Dental insurance
• Employee assistance program
• Employee discount
• Flexible schedule
• Flexible spending account
• Health insurance
• Health savings account
• Life insurance
• Paid time off
• Parental leave
• Professional development assistance
• Referral program
• Retirement plan
• Tuition reimbursement
• Vision insurance

Responsibilities

• Lead endpoint security engineering initiatives using Trellix ePO and related components to safeguard Windows and Linux endpoints.
• Design, configure, and maintain Trellix suite elements (ePO, Trellix Agent, DLP, HIPS, Policy Auditor, ABM, VSE) across mixed environments.
• Develop and deploy endpoint security policies for ENS modules (Threat Prevention, Firewall, Web Control) guided by DISA STIGs and business needs.
• Create and tune custom signatures, rules, and exceptions to address zero-day threats and operational requirements.
• Validate custom exceptions to ensure mission-critical processes run without compromising compliance.
• Oversee vulnerability management (ACAS/Nessus) and architect enterprise-wide scanning strategies, including Security Centers and Nessus deployment.
• Serve as final escalation point for complex scan issues, credentialing problems, and system communication failures.
• Configure automated reporting of compliance data to continuous monitoring systems and risk repositories.
• Integrate Trellix and ACAS with Splunk, XSOAR, and ServiceNow to automate workflows and strengthen incident response.
• Provide authoritative RMF support with ACAS-generated artifacts for A&A processes and RMF packages toward Authority to Operate.
• Lead the maintenance and scalability of test, development, and production environments in collaboration with Network and DevSecOps teams to bolster resilience.
• Deliver Tier 1–3 maintenance and incident response across the full cybersecurity portfolio, including ACAS, Trellix, Splunk, and XSOAR.
• Apply a deep understanding of DISA STIGs, NIST 800-53, and the RMF to guide risk management activities.

Requirements

• Active Top-Secret clearance with SCI or TS with the ability to obtain SCI.
• Experience with Nessus/ACAS and Trellix administration.
• Experience in Splunk operations within a clustered environment.
• Full-time availability of 40 hours per week, typically Monday through Friday; overtime may be required during peak periods.
• Ability to travel 5–10% within approximately 75 miles.
• Proficiency with MS Office applications (Excel, Word, Outlook, SharePoint, Project, Visio).
• Exceptional attention to detail and strong verbal and written communication, coupled with critical thinking, organizational, time-management, and problem-solving skills.
• Ability to work independently and as part of a team in a dynamic environment.
• Bachelor’s degree in Cyber or Engineering or a related field.
• 8 years of relevant experience in information security or a closely related field.
• DoD 8140 IAT certification readiness: possess, or be able to obtain, one of the Level II or Level III baseline certifications before start date (Level II examples: CCNA Security, GISCP, GSEC, Security+ CE, SSCP; Level III examples: CASP CE, CCNP Security, CISA, CISSP or Associate, GCED, GCIH).
• Required or preferred certifications: TS/SCI clearance (required), IAT Level II (required), IAT Level III (preferred).
• Experience with Splunk in clustered environments and ACAS/Nessus is explicitly required.

Technologies

• Trellix ePO
• Trellix Agent
• DLP
• HIPS
• Policy Auditor
• ABM
• VSE
• ACAS
• Nessus
• Windows
• Linux
• Splunk
• XSOAR
• ServiceNow
• Red Hat Enterprise Linux (RHEL) 8
• Red Hat Enterprise Linux (RHEL) 9

Work Schedule

5 Days (Mon – Fri); 8 hrs/Day; 40 hrs/week