Senior Security Researcher & Analyst - WAF Application Security Experts

Available Locations: London, United Kingdom, Bengaluru India & Singapore
About the Department
Cloudflare's Application Security organization builds and operates the systems that detect, classify, and mitigate malicious or abusive HTTP traffic across one of the largest networks on the Internet. Our products - including the Web Application Firewall (WAF), Bot Management, and Fraud Detection - protect millions of Internet properties from attacks and abuse in real time.
We combine large-scale data analytics, cutting-edge AI and ML models, and expert threat research to continuously evolve Cloudflare's detection and protection capabilities. The team brings together security researchers, analysts, and engineers who collaborate to identify new attack vectors, create innovative mitigations, and deliver protection at Internet scale.
What You'll Do
As a WAF Application Security Expert, you'll focus on researching, designing, and improving detection logic and rules that protect customer applications from the latest web threats.

• Analyze web exploits and vulnerability patterns (RCE, SQLi, XSS, SSRF, deserialization, etc.) and build corresponding WAF mitigations.
• Collaborate with product engineering and data teams to tune detection efficacy - reducing false positives/negatives across large-scale, high-volume traffic.
• Develop, test, and deploy WAF managed rules and exploit signatures based on public CVEs, threat intelligence, and internal telemetry.
• Perform targeted penetration testing and red-team style assessments to uncover gaps in Cloudflare's WAF coverage and propose mitigations.
• Leverage strong coding skills to automate rule validation, testing pipelines, and data analysis workflows.
• Conduct research on attacker behaviors, evolving exploit chains, and web attack automation trends.
• Produce internal and external research reports summarizing Internet-wide attack trends and WAF efficacy insights.
• Collaborate closely with Bot Management, Fraud, and ML teams to design cross-signal detection frameworks that unify WAF and behavioral defenses.
• Communicate complex technical findings clearly to both engineering and non-technical audiences.

What You Bring

• Bachelor's or Master's degree in Computer Science, Information Security, or equivalent practical experience.
• 2+ years of experience in Web Application Security, WAF rule development, incident detection, or threat research.
• Deep understanding of web protocols (HTTP/HTTPS), common web vulnerabilities, and exploitation techniques (OWASP Top 10).
• Proven experience writing and optimizing WAF rules or custom detection logic.
• Hands-on experience with vulnerability analysis, exploit reproduction, or reverse engineering.
• Strong analytical mindset and comfort working with large data sets (SQL, ClickHouse, BigQuery, etc.).
• Proficiency in at least one programming language such as Python, Go, or Rust for building automation tools or analysis scripts.
• Familiarity with Grafana or equivalent visualization tools to track rule performance and attack trends.
• Strong written and verbal communication skills - able to document, present, and collaborate effectively.
• Experience working in fast-paced environments with production-scale systems.

Bonus Points

• Experience with columnar databases like ClickHouse and advanced SQL query optimization.
• Familiarity with machine learning for security analytics (feature extraction, anomaly detection, model evaluation).
• Solid understanding of Linux/UNIX systems, TCP/IP networking, and proxy architectures.
• Prior publications or conference presentations (e.g., Black Hat, DEF CON, BSides).
• Contributions to open-source WAF projects or web security tools.
• Knowledge of WAF and bypassing WAF products with novel techniques.
• Experience on bug bounty/CTF is plus.