Endpoint Security Engineer

Job Type: Full- Time Workplace Type: Remote in the areas of Morrisville, NC or Falls Church, VA Clearance: TS/SCI Must be a U.S. Citizen Benefits: Medical, dental, and vision coverage, 401k matching, generous PTO, paid holidays, professional training opportunities, and even pet insurance to ensure your furry friends are cared for too. Job Summary Castalia Systems is seeking an Endpoint Security Engineer to support our Intelligence Client’s mission sets. As an Endpoint Security Engineer you will design, deploy, and operationalize active, behavior-based endpoint detection and response (EDR/XDR) capabilities across one of the largest private operational fleets in North America. Protecting an enterprise comprising 600,000+ employees and 30,000+ physical sites , you will maintain rigorous security posture across traditional end-user computing (EUC) devices (laptop, desktop, mobile devices & retail terminals), on-premise physical & virtual servers & containerized workloads, and dynamic multi-cloud workloads (AWS, Azure, GCP). In this role, you will balance proactive protection with business continuity—partnering directly with end-users and application owners to tune policies and eliminate operational friction, while providing tier-3/tier-4 technical escalations to Security Operations Center (SOC) analysts and IT Operations staff during active investigations. Roles and Responsibilities A qualified candidate will perform the following duties and responsibilities, but are not limited to: Fleet-Wide Behavioral Defense & Control Engineering: Engineer, deploy, and maintain Next-Gen Antivirus (NGAV) and Endpoint Detection & Response (EDR/XDR) agents (e.g., CrowdStrike Falcon, Microsoft Defender for Endpoint, SentinelOne) across hundreds of thousands of heterogeneous endpoints. Implement active behavioral protections against zero-day malware, living-off-the-land binaries (LotLBs), fileless execution, and credential dumping. Application Owner & End-User Engagement (Business Impact Management): Serve as the primary technical partner to application owners and business units, establishing baseline behavior profiles to minimize false positives, performance degradation, or operational downtime across critical retail, logistics, and supply chain applications. Manage allowlisting, exception workflows, and phased ring deployments (canary/pilot/production) to ensure silent, high-efficacy protection without disrupting day-to-day warehouse or logistics operations. SOC & IT Operations Event Investigation Support: Act as endpoint security escalation lead for SOC analysts during high-severity threat detection and response events. Act as endpoint operations escalation lead for IT administrators during high-impact event investigation and remediation efforts. Perform advanced host forensics, process-tree reconstruction, memory analysis, and script-based live remediation (e.g., host isolation, automated artifact collection, registry rollbacks). Hybrid & Multi-Cloud Workload Protection: Extend endpoint security standards across private data center virtualization layers (VMware/Nutanix) and ephemeral multi-cloud infrastructure (EC2, Azure VMs, Compute Engine, containerized hosts). Control Efficacy & Continuous Validation: Continuously measure and test security control efficacy using automated attack simulation (BAS) tools and Purple Team exercises. Track and report on agent health, tamper-resistance, telemetry pipeline integrity, and coverage metrics aligned with enterprise asset management systems. Required Qualifications: A minimum of 7+ years of progressive experience in technical cybersecurity engineering or infrastructure security roles. At least 3–5 years directly engineering and administering enterprise-grade EDR/XDR platforms across 50,000+ endpoints in a distributed hybrid environment. Demonstrated track record supporting active SOC investigations and collaborating cross-functionally with system owners in large-scale enterprise environments. Bachelor’s degree in Computer Science, Cybersecurity, Information Systems, or equivalent practical enterprise experience. EDR/XDR Engineering: Expert-level proficiency administering enterprise-scale endpoint platforms across Windows, macOS, Linux distributions, and container runtime environments. Behavioral Analysis & Threat Hunting: Deep mastery of process lineage, behavioral IOAs (Indicators of Attack), Sysmon telemetry, and detection authoring using query languages such as SQL, KQL (Kusto Query Language) , Splunk SPL , or YARA . Hybrid Infrastructure & OS Internals: Deep understanding of Windows/Linux kernel architectures, API hooking, hypervisor isolation, and multi-cloud workload identity integrations. Automation & Scripting: Strong programming/scripting abilities in PowerShell , Python , or Bash to orchestrate fleet-wide remediations and automate policy compliance at scale. Artificial Intelligence & Machine Learning : Fluency applying appropriate AI/ML technologies and analytics platforms (Splunk, Databricks, Elastic) to streamline and/or automate activities including but not limited to research, developing documentation, and supporting development of executive communications. Fluency applying appropriate AI/ML technologies to automate security activities to improve timeliness or full automation of event response activities. Abilities & Core Competencies Stakeholder Empathy & Impact Analysis: Proven ability to balance stringent security controls with business operational velocity, ensuring minimal disruption to end-user productivity and mission-critical COTS/proprietary software. Crisis Leadership & Composure: Capable of methodically triaging active enterprise threats under pressure and articulating complex host-based attacks to executive leadership. Operational Scale Management: Mindset geared toward "Infrastructure-as-Code" and policy automation rather than manual device-by-device intervention. Preferred Certifications GIAC Certified Enterprise Defender (GCED) , GIAC Certified Incident Handler (GCIH) , or GCFA (Forensic Analyst) . CISSP (Certified Information Systems Security Professional). Physical Requirements/Work Environment Normal Office environment Travel As needed Company Description Castalia Systems is a proven business partner providing mission critical solutions to the Federal Government. We provide cutting edge solutions from Securing and Managing Data to Systems Engineering and Development. Castalia Systems is a pioneer in Artificial Intelligence Design and Application. With our vast knowledge of our customers’ needs and relevant technology, our team is able to bring successful solutions to every mission. We are one-upping our competitors by providing premium IT solutions and platforms with cutting-edge technology so it’s so evident when you compare us with anyone. Disclaimer Castalia Systems is an equal employment opportunity and affirmative action employer and strives to comply with all applicable laws prohibiting discrimination based on race, color, creed, sex, sexual orientation, age, national origin, or ancestry, physical or mental disability, veteran status, marital status, HIV-positive status, as well as any other category protected by federal, state, or local laws. All such discrimination is unlawful, and all persons involved in the operations of the company are prohibited from engaging in this type of conduct.