Senior Cloud Platform Security Engineer

CoStar • Arlington, VA

3d • Hybrid

About The Position

CoStar Group is a leading global provider of commercial and residential real estate information, analytics, and online marketplaces. The company is on a mission to digitize the world’s real estate. CoStar builds and operates web applications related to real estate, including Apartments.com, Homes.com, Lands.com, CoStar.com, and many others. The product platform security engineering group builds and operates centralized controls using infrastructure as code, scripting, and API integrations to scale security across all web applications in a consistent manner. This role focuses on the product platform security environment, which consists of commercial and custom-developed security controls that run within the IDE, the CI/CD system, across cloud and Kubernetes platforms, and our product edge.

Requirements

• Bachelor’s Degree required from an accredited, not for profit, in person, university or college (preferably in Computer Science, Cybersecurity or a related field).
• A track record of commitment to prior employers.
• 6+ years of hands-on security engineering experience, with depth in at least one and meaningful exposure to others among the following domains: Securing cloud-native environments (AWS preferred), Kubernetes platform hardening or monitoring, CI/CD pipelines, containerized application deployments, and IAC, and software supply chain security.
• Demonstrated track record of taking security initiatives from scoping through production rollout and operational ownership.
• Demonstrated ability to author scripts or IAC from scratch in either Python, PowerShell, Ansible, CloudFormation, Terraform, or similar language.
• Securing AI-powered applications, including threat modeling for LLM-based features, MCP server implementations, or agentic systems.
• Experience working in a software development environment with a mature CI/CD.
• Passion for solving complex challenges, innovating, and engaging in your work.

Nice To Haves

• A self-starter who can advance the platform security program and follow-through ideas to completion.
• Experience with tools and services like AWS GuardDuty, Security Hub, EKS, OPA/Gatekeeper, Falco, Wiz, Datadog, Prisma Cloud, Orca, Upwind, Snyk, or similar.
• Familiarity with software supply chain security, including SBOM generation, dependency vulnerability management, build provenance, and artifact signing.
• Knowledge of infrastructure operations across databases, network, and system administration.
• Effective use of AI tools as a force multiplier for engineering work, with judgment about when AI accelerates work versus when it creates rework.
• Ability to communicate with different levels of leadership conveying risk and driving urgency for risk remediation.
• Familiarity with zero trust principles and cloud-native access controls (e.g. IAM roles, service meshes).
• Ability to mentor and train team members to prioritize security efforts effectively.
• Hands-on experience implementing security tools into CI/CD pipelines.
• Experience testing serverless cloud deployments.

Responsibilities

• Enforce security posture across AWS, GCP, and Azure through preventative controls (SCPs, organization policies, IAM guardrails) and detective controls (Wiz, native cloud security services).
• Build detection patterns and escalation paths in partnership with incident response.
• Drive validation methodology and operational rigor across acquisitions and new environments.
• Lead workload protection strategy across EKS clusters, including runtime monitoring, admission control, network policy, and secrets management.
• Drive sensor coverage validation, incident response readiness, and security guardrails that scale across the portfolio.
• Partner with product engineering on securing AI-powered features, MCP server implementations, and agentic workflows across the portfolio.
• Lead threat modeling for new AI surfaces, build guardrails and detection patterns for prompt injection and unauthorized tool use, and shape security standards as the company expands AI capabilities into customer-facing products.
• Integrate automated scanning tools into CI/CD pipelines, implement IaC solutions, and drive automated remediation processes.
• Work closely with product dev teams to provide feedback on secure coding practices, proactively guide them on risk remediation.

Benefits

• Generous compensation and performance-based incentives.
• Internal training.
• Tuition reimbursement.
• 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 Employee Resource Groups
• Complimentary gourmet coffee, tea, hot chocolate, fresh fruit, and other healthy snacks

What This Job Offers

• Job Type: Full-time
• Career Level: Senior