At least one of an HTTP request message and an HTTP response message is intercepted. A corresponding HTTP message model is identified. The HTTP message model includes a plurality of message model sections. Additional steps include parsing a representation of the at least one of an HTTP request message and an HTTP response message into message sections in accordance with the message model sections of the HTTP message model; and binding a plurality of security rules to the message model sections. The plurality of security rules each specify at least one action to be taken in response to a given condition. The given condition is based, at least in part, on a corresponding given one of the message sections. A further step includes processing the at least one of an HTTP request message and an HTTP response message in accordance with the plurality of security rules. Techniques for developing rules for a web application server firewall are also provided.