OpenWAF

OpenWAF is designed to protect web applications from various threats, including injection attacks, cross-site attacks, and information leaks, by leveraging a robust and flexible architecture.

At its core, OpenWAF is built on the nginx_lua API, utilizing OpenResty to analyze HTTP request information. It consists of two primary engines: a rule engine and a behavior analysis engine. The rule engine, inspired by ModSecurity and lua-resty-waf, analyzes individual requests against predefined rules to detect and mitigate security exceptions. These rules can be dynamically updated to address emerging vulnerabilities. The behavior analysis engine tracks request information to provide a comprehensive view of application behavior.

Operationally, OpenWAF integrates tightly with Nginx, using various Lua scripts to handle different phases of the request lifecycle, such as access, header filtering, body filtering, and logging. This integration allows for fine-grained control over request processing. For example, the server_ssl directive enables or disables SSL connections to backend servers, and the use of variables like $twaf_upstream_server simplifies proxy configurations.

Key operational considerations include the need for careful rule management to avoid false positives and performance degradation. The system supports dynamic rule updates, but this requires ongoing maintenance and testing to ensure rules are effective and do not introduce unintended consequences. Additionally, while OpenWAF offers detailed logging capabilities, managing log data and retention can become complex, especially in high-traffic environments. Overall, OpenWAF provides a powerful and customizable WAF solution, but its effectiveness depends on thorough configuration and ongoing management.