What Is a Web Application Firewall?

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A Web Application Firewall (WAF) can be an important tool in your online security arsenal. WAFs work by inspecting, monitoring, and filtering all traffic between the users and your web applications. This helps web applications protect against attacks targeting their vulnerabilities. In this blog post, we will explore the basics of a Web Application Firewall, from what it is and how it works to how it differs from a traditional firewall or an Intrusion Detection System (IPS).

What is a Web Application Firewall (WAF)?

A Web Application Firewall (WAF) is an application firewall that filters, monitors, and blocks HTTP traffic to and from a web service, helping protect a organization’s web applications. WAFs can be hardware devices, software programs, or cloud-based services. They are designed to protect web applications from a variety of attacks, such as SQL injection, Cross-Site Scripting (XSS), and session hijacking. Powerful automation and sophistication in today’s cyber threats have led to the creation of more specific, effective security tools like the Web Application Firewall.

How does a Web Application Firewall work?

Web Application Firewalls work by inspecting each incoming request and comparing it against a set of rules. If the request does not meet the criteria outlined in the rules, it is blocked; Conversely, if the request does meet the criteria, it is allowed through and processed by the web application. In that sense, WAFs can be either positive or negative security models, depending on your configuration approach:

  • A positive security model, also known as a whitelist, only allows requests that meet specific criteria while blocking all others. A positive-model WAF is more secure but can also be more difficult to manage, as even a small change to the rules can result in false positives (legitimate requests being blocked).
  • A negative security model, also known as a blacklist, blocks requests on the premise that most attackers are using known attack vectors or public exploits. Although a negative-model WAF may appear easier to manage, it requires to stay up to date on new exploits as they become public, which can be a difficult and time-consuming task.

Configuring a WAF can be a delicate balance; too strict and you risk blocking legitimate traffic; too flexible and you leave yourself vulnerable to attacks. Striking the right balance is crucial to the effectiveness of your Web Application Firewall.

How does aWAF differ from a firewall ?

WAF vs. firewall

A Web Application Firewall (WAF) is designed specifically to filter traffic to and from web applications, inspecting the content of each request and blocking malicious requests. Traditional firewalls, on the other hand, are designed to filter traffic based on a set of predefined rules, such as IP addresses or port numbers. In that perspective, WAFS are more specific and can provide better protection for web applications, whereas firewalls are more general and can provide better protection for networks. That being said, WAFs and traditional firewalls should be used together.

WAF vs. Intrusion Detection System (IDS)

A Web Application Firewall (WAF) is designed specifically to filter traffic to and from web applications, whereas an IDS is designed to watch all network traffic, including traffic to and from web applications. WAFs inspect the content of each request and can block malicious requests before they reach the web server; An IDS looks for anomalies in network traffic and alert you when an attack is underway, blocking all traffic. Given their functional differences, WAFs and IDSs complement each other and should be used together.

WAF vs. Endpoint security software

Endpoint security software is a type of software providing security for any type of device connecting to your network, from laptops and smartphones to digital printers. WAFs are designed specifically to filter traffic to and from web applications, inspecting the content of each request and blocking malicious requests before they reach the web server; Endpoint security software looks for malware and other threats on each and everyone of your network devices, blocking traffic from any of them that do not meet your security policy.

What are the main benefits of a WAF?

A Web Application Firewall can provide the following benefits:

Boost web application security

By inspecting all traffic going to and from any web applications, a Web Application Firewall can block malicious requests that traditional firewalls and other security devices would miss. This helps boost the overall security of your web applications. For example, WAFs can protect against SQL injection attacks, Cross-Site Scripting (XSS) attacks, and other types of web application attacks.

Help meet compliance requirements

The effectiveness of a Web Application Firewall on the application lawyer can help you meet compliance requirements, such as PCI-DSS and HIPAA. These security standards require that organizations take measures to protect their web applications and data from common attacks. Either for PCI-DSS or HIPAA, the data collected, stored, and transmitted is highly sensitive.

Reduce false positives

In cybersecurity, a false positive is an alert that incorrectly indicates that a vulnerability is present. False positives can be caused by a number of things, such as misconfigured security devices or rules, normal network traffic, and so on. WAFs can help reduce false positives by providing more granular control over what traffic is allowed through to the web server.

Final thoughts

A Web Application Firewall can be a vital part of any organization’s security posture. WAFs provide better protection for web applications than traditional firewalls, help meet compliance requirements, and can reduce false positives. When used together with other security devices and measures, WAFs can help protect your organization from a variety of attacks. Regular web application penetration testing will also help you find and secure unknown entry points and align your processes and people with cybersecurity best practices. Contact us if you need help improving your application security.

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