With a pressing need to do more to protect Web applications from attack, IT staff can turn to a new class of specialized firewalls that do a great deal to protect Web servers, Web applications, and connected internal servers and databases from attack.

Each of the three Web application firewalls eWEEK Labs reviews here—Kavado Inc.'s InterDo 3.0, Sanctum Inc.'s AppShield 4.0 and Teros Inc.'s Teros-100 APS (Application Protection System) 2.1.1—provides next-generation attack defense through a deep understanding of how HTML applications function.

All three products go through an HTML parsing phase where they learn the form field, application structure and cookie usage for each Web page. The firewalls use this information to dynamically inspect all incoming requests. They can therefore block requests that modify hidden fields or cookies or submit malformed requests, such as very long parameters or parameters containing script or SQL commands.

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