Senior Security Engineer

We are seeking a Senior Security Engineer with experience in Network, SaaS, and AI Security to help evolve and safeguard CoStar’s enterprise security posture across network infrastructure, cloud services, SaaS platforms, and emerging AI systems. This role expands upon traditional network security engineering to include SaaS security governance and AI security risk management, supporting both human and machine‑driven workflows. The ideal candidate brings deep technical capability, strong security judgment, and the ability to communicate security concepts effectively to both technical and non‑technical audiences across the enterprise. This position can be located in Arlington or Richmond, VA and is in office Monday through Thursday and work from home on Friday. Responsibilities Provide engineering expertise to ensure enterprise network changes are designed and implemented securely (on‑prem and cloud). Audit existing network designs and infrastructure configurations and recommend improvements to security posture. Evaluate firewall change requests across on‑premise and cloud environments. Design, enforce, and audit policies for Next Generation Firewalls (NGFW), load balancers, routers, switches, and wireless infrastructure. Manage Secure Service Edge (SSE) platform SaaS Security Partner with application owners and third‑party risk teams to review SaaS security architecture and control effectiveness. Operate and tune SaaS security tooling (e.g., CASB/SSE capabilities) to detect risky behavior, misconfigurations, and data exfiltration paths. Define and enforce SaaS security standards for logging, identity integration, and least‑privilege access. Support SaaS incident investigation and remediation efforts in coordination with legal, privacy, and compliance teams. Develop reusable SaaS security review patterns and documentation for engineering and procurement teams. Assess security risks associated with AI platforms, copilots, and agent‑based systems, including model access controls, prompt/data leakage risks, and tool/plugin abuse. Partner with engineering teams to design security controls for AI‑assisted workflows and developer tools. Contribute to governance models for AI usage, including enforcement of network, identity, and data security boundaries. Monitor AI‑related telemetry and logs to identify anomalous behavior, data exposure, or misuse patterns. Support threat modeling and risk assessments for AI integrations with enterprise systems and SaaS platforms. Stay current on AI security threats, abuse patterns, and control frameworks, translating them into actionable enterprise safeguards. Basic Qualifications Bachelor’s Degree is required from an accredited, not for profit, in‑person university or college. A track record of commitment to prior employers 5+ years of experience in Information Security or Security Engineering. One or more industry‑recognized certifications (e.g., CISSP, SANS/GIAC, CCNA, equivalent). Strong experience securing AWS networking (NACLs, Security Groups, ALB/NLB, Transit Gateway, Network Firewall). Hands‑on experience with NGFWs, WAFs, load balancers, and enterprise network segmentation. Strong scripting or automation skills (Python, PowerShell, or similar). Deep understanding of subnetting, routing, and network isolation principles. Experience with SaaS security platforms, CASB, or SSE tooling. Preferred Qualifications And Skills Familiarity with identity‑driven security models (SSO, OAuth, API tokens, service principals). Working knowledge of Azure DevOps, Terraform, or infrastructure‑as‑code workflows. Experience operating in large, complex enterprise environments. Ability to produce high‑quality technical documentation and security standards. Strong communication and collaboration skills across technical and non‑technical teams. Exposure to AI systems, model‑assistant tooling, or developer copilots in an enterprise context. What’s In It For You When you join CoStar Group, you’ll experience a collaborative and innovative culture working alongside the best and brightest to empower our people and customers to succeed. We offer you generous compensation and performance‑based incentives. CoStar Group also invests in your professional and academic growth with internal training, and tuition reimbursement. Our Benefits Package Includes (but Is Not Limited To) Comprehensive healthcare coverage: Medical / Vision / Dental / Prescription Drug Life, legal, and supplementary insurance Virtual and in person mental health counseling services for individuals and family Commuter and parking benefits 401(K) retirement plan with matching contributions Employee stock purchase plan Paid time off On‑site fitness center and/or reimbursed fitness center membership costs (location dependent), with yoga studio, Pelotons, personal training, group exercise classes Access to CoStar Group’s Diversity, Equity, & Inclusion Employee Resource Groups Complimentary gourmet coffee, tea, hot chocolate, fresh fruit, and other healthy snacks We welcome all qualified candidates who are currently eligible to work full‑time in the United States to apply. However, please note that CoStar Group is not able to provide visa sponsorship for this position. CoStar Group is an Equal Employment Opportunity Employer; we maintain a drug‑free workplace and perform pre‑employment substance abuse testing. #J-18808-Ljbffr