Customer portals, e-commerce sites, mobile app back ends and APIs are now among a business's most valuable assets. Because they face the internet, they are also attackers' first target. What's more, most of these attacks hide inside legitimate-looking web requests that pass straight through a traditional firewall.
What Is a WAF?
A WAF (Web Application Firewall) is a security solution that inspects HTTP/HTTPS traffic to web applications before it reaches them and blocks malicious requests. It works like a shield in front of the application: it looks at the content of every request, stops the ones that carry signs of an attack and passes clean traffic on to the application.
How a WAF Differs from a Traditional Firewall
A traditional firewall looks at which address traffic goes from and to, and over which port. A request to your website arrives on an allowed port, so it passes the traditional firewall; the firewall cannot tell whether the request carries an SQL injection attack. A WAF, by contrast, inspects the request's content, parameters and behavior at the application layer. That is why the two are not alternatives but complements.
Which Attacks Does a WAF Stop?
- SQL injection: malicious queries aimed at taking over the database
- XSS (Cross-Site Scripting): attempts to run malicious code in users' browsers
- Other common web application vulnerabilities in the OWASP Top 10
- Malicious bots, credential stuffing and content scraping
- Abuse of APIs and unauthorized data harvesting
- Application-layer DDoS attacks
Types of WAF
A WAF can run on premises as an appliance or virtual machine, as a cloud service, or in a hybrid setup that combines both. In recent years WAFs have been evolving into WAAP (Web Application and API Protection) solutions that bring bot management, API security and DDoS protection together on one platform. The right model depends on where your applications run, your traffic volume and your regulatory requirements.
What to Watch For in a WAF Project
A WAF is only as good as its tuning. Left on default rules, a WAF either misses attacks or blocks real users and costs business. The right approach is to learn the application's normal traffic in monitoring mode first, tune the rules specifically to the application and move to blocking mode step by step. As the application changes, the rules must be kept up to date too.
A WAF does not fix the vulnerabilities in an application; it blocks attacks that try to exploit them. That is why it delivers the most value alongside regular penetration testing and secure software development practices.
WAF with Novus BT
WAF is one of Novus BT's strongest fields. Our team consists of engineers who are highly skilled in WAF projects across on-premises, cloud and hybrid environments and have gained deep field experience. We get to know your applications, design the rules around them and manage deployment and tuning without disruption.
To assess the security of your web applications and APIs, you can schedule a free initial consultation with our experts.