Cloudflare WAF

The Cloudflare Web Application Firewall (WAF) manages protecting web and API applications from a myriad of threats, including common vulnerabilities, zero-day exploits, and malicious traffic. At its core, the Cloudflare WAF filters incoming requests based on predefined rulesets, which can be managed, custom, or a combination of both.

Technically, the WAF leverages a robust matching engine that supports the wirefilter syntax using the Rules language. It includes managed rulesets, such as the Cloudflare Managed Ruleset and the Cloudflare OWASP Core Ruleset, which are regularly updated to protect against known attacks and zero-day vulnerabilities. These rulesets are designed to balance protection with minimal false positives, with the Cloudflare Managed Ruleset being signature-based and the OWASP Core Ruleset being score-based, allowing for adjustable paranoia levels.

Operationally, the WAF integrates with the Cloudflare global network, processing a vast volume of HTTP requests per second. It provides various traffic detections, including bot score, attack score, and malicious uploads scanning, which enrich requests with metadata to aid in detection and mitigation. The rule execution order is critical, with rules evaluated in a specific sequence: IP Access Rules, custom rulesets, rate limiting rules, and finally managed rules. If a rule matches with a terminating action, the evaluation stops, and the action is executed immediately.

Key operational considerations include the need to monitor and adjust rulesets regularly, as the default settings may not cover all specific application needs. The Security Analytics and Security Events dashboards are essential for reviewing traffic and mitigated requests, allowing for fine-tuning of the WAF configuration. Additionally, enterprise customers can leverage Cloudflare Logs for detailed insights into HTTP requests and security events.