What is a Web Application Firewall (WAF)?

by Amrita Mitra | Mar 9, 2017 | CCNA, CCNP, CompTIA, Data Breaches and Prevention, DoS and DDoS Prevention, End Point Protection, Firewall, Information Security, Malware Prevention, Network Security, Security Fundamentals

make a connection to the proxy-based firewall, which makes a separate connection to the requested computers after carefully inspecting the network packets. Thus, it can provide strong security.

A proxy-based Firewall can also help in the following ways :

Caching – It can cache regularly requested web contents and thus reduce the load on the web servers by reducing repeated requests to back-end servers.
Compression – Proxy-based Web Application Firewall can compress certain web contents that can be decompressed later by the browser.
SSL Acceleration – Proxy-based Web Application Firewalls can speed up SSL processing and reduce the burden on back-end web servers by using hardware-based SSL decryption.
Load Balancing—Proxy-based Web Application Firewalls can distribute incoming requests to multiple servers behind them, improving performance and reliability.
Connection Pooling – Proxy-based Web Application Firewalls can reduce back-end server TCP overhead by allowing multiple requests to use the same back-end connection.

What are Host-based Web Application Firewalls?

A Host-based Web Application Firewall can examine the information that passes through the system calls through the network stack and filter traffic based on that. It can hook into socket calls and filter the connections between the application layer and the lower layers in the OSI reference model based on some predefined rules. It applies the filtering rules on a per-process basis instead of a per-port basis.

Host-based Web Application Firewalls can examine data packets’ process IDs and match them against a pre-defined ruleset for that process. They can also have complex rulesets for standard services, such as sharing services.

AppArmor and TrustedBSD MAC Framework are examples of some commonly used Host-based Web Application Firewalls.

The benefits of an application layer firewall are, as already said, that it can understand certain application layer protocols like FTP, HTTP, DNS, or web browsing and filter network traffic of an unwanted protocol. It can also look through non-standard ports to detect if any protocol is being abused.

Host-based Web Application Firewalls can protect against threats like SQL Injection, Cross-Site Scripting or XSS, Session Hijacking, Parameter or URL tampering, buffer overflows, etc.

I hope this helps. However, interested readers who want to know more about how different web application attacks work and how to prevent them may want to refer to the book “Web Application Vulnerabilities And Prevention.”

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