Systems Engineer III

Reflexive Concepts; Fort Meade (MD); On-site; USD 140,000 - 190,000; Full time

Job summary

Reflexive Concepts is seeking a skilled Systems Engineer III to join our team supporting the NSA Enterprise Endpoint Detection and Response (EDR) program. The role focuses on architecting, deploying, and optimizing end-to-end endpoint security platforms including Microsoft Defender for Endpoint and Trellix HX across hybrid environments.

You will translate threat intelligence into technical IOCs, mentor engineers, and advise government stakeholders on risk, performance, and compliance, while

Qualifications

• Twenty (20) years of experience supporting projects and programs similar in scope and complexity.
• Bachelor's Degree in Computer Science or a related field.
• MDE architecture, deployment via MECM/SCCM or Intune, and advanced hunting using KQL.
• Trellix HX deployment and management in restricted networks; OpenIOC and YARA rule creation.
• DoD 8570/8140 IAM Level II or III baseline certifications.

Responsibilities

• Lead the lifecycle engineering and scale-out architecture of MDE and Trellix HX across hybrid environments.
• Author complex system engineering and implementation plans; tune configurations and exclusion policies.
• Collaborate with threat hunting and intelligence analysts to translate actionable threat intelligence into IOCs using KQL and YARA.
• Act as a primary technical advisor to Government stakeholders on system risks and engineering considerations.
• Provide advanced forensic support to the SOC during high-priority incidents.
• Mentor junior and mid-level engineers within the program.

Skills

MDE Expertise

Trellix HX Expertise

OS Forensic Knowledge

DoD IAM Certifications (II/III)

Education

Bachelor's Degree in Computer Science or related field

Tools

MECM/SCCM

Intune

Kusto Query Language (KQL)

YARA rules

Job description

Reflexive Concepts is seeking a skilled Systems Engineer III to join our team!

Qualifications

• Twenty (20) years of experience supporting projects and programs similar in scope and complexity
• Bachelors Degree in Computer Science or a related field

Duties and Responsibilities

• The Senior Systems Engineer (Level 3) serves as a principal technical leader and subject matter expert within the National Security Agency's Enterprise Endpoint Detection and Response (EDR) Program. Operating in a highly classified, multi-domain infrastructure, the successful candidate will drive the strategic architectural design, end-to-end integration, deployment, and optimization of premier endpoint security platforms, specifically Microsoft Defender for Endpoint (MDE) and Trellix HX. This critical role bridges high-level systems architecture with operational defense capabilities, ensuring total endpoint visibility, robust threat containment, and resilient configuration management across all enterprise and mission-critical assets to defend national security infrastructure against sophisticated cyber threats.
• Lead the lifecycle engineering and scale-out architecture of MDE and Trellix HX across hybrid environments, including on-premises, cloud, and virtual desktop infrastructures (VDI), to include authoring complex system engineering and implementation plans, tuning agent configurations and exclusion policies to eliminate mission friction, and monitoring overall endpoint health at scale
• Collaborate closely with threat hunting and intelligence analysts to translate actionable threat intelligence into custom technical indicators of compromise (IOCs), utilizing Kusto Query Language (KQL) and YARA rules
• Act as a primary technical advisor to Government stakeholders on system risks and engineering considerations
• Provide advanced forensic support to the SOC during critical high-priority incidents
• Actively mentor junior and mid-level engineering personnel within the program

Required

• Microsoft Defender for Endpoint (MDE) Expertise: proven engineering experience with MDE architecture, deployment strategies via MECM/SCCM or Intune, policy ring management, and advanced hunting using Kusto Query Language (KQL)
• Trellix HX Expertise: demonstrated experience engineering, deploying, and managing Trellix HX (formerly FireEye) controllers and agents within air-gapped or highly restricted networks, including the creation of OpenIOC and YARA rules
• Operating System & Forensic Knowledge: in-depth technical understanding of Windows, Linux, and macOS internals, including file systems, registry structures, and process execution mechanics
• Professional Standards: compliance with DoD 8570/8140 IAM Level II or III baseline certifications

Desired

• Vendor Certifications: Microsoft Certified: Security Operations Analyst Associate (SC-200), Azure Security Engineer Associate (AZ-500), or Trellix Certified Engineering credentials
• Methodologies & Toolsets: experience with Model-Based Systems Engineering (MBSE), Cameo, and workflow management within the Atlassian Suite (Jira, Confluence)
• Technical Frameworks: familiarity with NSA Technical Manual Standards (e.g., NSA DS-89) and defense-in-depth engineering principles
• Core Competencies: strong record of team collaboration, exceptional transparency in managing high-consequence infrastructure, and an aptitude for developing technical leadership pipelines