Senior Information System Security Engineer

This senior information system security engineer role focuses on leading Trellix (ePO) and ACAS (Nessus) toolsets, providing RMF and ATO support, and applying secure-by-design principles across the SDLC for mission-critical assets at Amentum in Warrenton, Virginia. The position is onsite and requires close collaboration with cross-functional teams to safeguard information systems.

Responsibilities

• Ecosystem Management: Design, configure, and maintain Trellix components (ePO, Trellix Agent, DLP, HIPS, Policy Auditor, ABM, VSE) across Windows and Linux environments.
• Policy Development: Create and deploy endpoint security policies for ENS modules (Threat Prevention, Firewall, Web Control) aligned with DISA STIGs and organizational needs.
• Threat Mitigation: Develop custom signatures, rules, and exceptions to address zero-day threats and operational requirements.
• Operational Continuity: Validate custom exceptions to ensure uninterrupted operation of mission-critical processes while maintaining compliance.
• Architecture & Strategy: Design enterprise-wide vulnerability scanning strategies and oversee deployment of Security Centers and Nessus scanners.
• Advanced Troubleshooting: Serve as the final escalation point for complex scan issues, credentialing problems, and system communication failures.
• Risk Reporting: Configure automated reporting of compliance data to continuous monitoring systems and risk-scoring repositories.
• Tool Orchestration: Integrate Trellix and ACAS with Splunk, XSOAR, and ServiceNow to automate workflows and strengthen incident response.
• RMF Support: Provide authoritative recommendations and ACAS-generated artifacts to support Assessment and Authorization processes and RMF packages for ATO.
• Strategic Oversight: Maintain and scale test, development, and production environments, collaborating with Network and DevSecOps teams to improve resilience.
• Multi-Tier Support: Deliver Tier 1–3 maintenance and incident response for the full cybersecurity portfolio including ACAS, Trellix, Splunk, and XSOAR.
• Compliance Mastery: Maintain deep understanding of DISA STIGs, NIST 800-53, and the RMF guidelines.

Requirements

• Active Top-Secret clearance with SCI or TS eligibility to obtain SCI.
• Experience with Nessus/ACAS and Trellix administration.
• Experience in a Splunk role within a Splunk Clustered Environment.
• Minimum 8 years of relevant experience.
• Availability for a 40-hour work week, typically Monday through Friday, with overtime during critical periods as needed.
• Travel availability of 5–10 percent, primarily within 75 miles.
• Proficiency with MS Office applications: Excel, Word, Outlook, SharePoint, Project, Visio.
• Excellent attention to detail, strong verbal and written communication, and solid analytical and organizational abilities.
• Ability to work independently and as part of a team in a dynamic environment.

Technologies

• Trellix (ePO), Trellix Agent, DLP, HIPS, Policy Auditor, ABM, VSE
• Nessus, ACAS
• Splunk, XSOAR, ServiceNow
• Windows, Linux
• MS Office Suite: Excel, Word, Outlook, SharePoint, Project, Visio

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

Other Responsibilities

• Safety - Amentum maintains a safety culture; all employees are responsible for a safe work environment, completing required training, and participating in emergency tasks as applicable.
• Quality - Adhere to the Amentum Quality Policy and related quality systems to meet customer expectations and conform to contracts.
• Procedure Compliance - Read, understand, and implement general and specific operational, safety, quality, and environmental requirements of all plans, procedures, and policies relevant to the role.

Education

Bachelor's degree in Cyber and/or Engineering is required.

Experience

• Trellix Administration: 5 years (Required)
• Splunk: 6 years (Required)
• ACAS/Nessus: 8 years (Required)

Licenses and Certifications

• TS/SCI (Required)
• IAT Level II (Required)

Location

Warrenton, VA 20186 (Onsite, in person).

Travel Requirements

5 to 10 percent travel, primarily within 75 miles.

Work Location

In person