Web Application Firewall: Everything To Know in 6 Easy Steps


Websites and web applications are the primary entry points targeted by cybercriminals because they are public and the most exposed assets of an organization. Some popular forms of attack performed on web applications and servers are the cross-site scripting (XSS), SQL injection (SQLi) attacks, and Distributed Denial of Service (DDoS) attacks.

Such attacks can cause massive damage to the data as well as the reputation of a company. That is why companies use modern security applications and tools to protect their organizational data from breaches and cyber-attacks. One of the most common web security applications is the firewall. It can be a security device that is hardware or software that protects the systems from unofficial access.Let us understand the web application firewall in detail

  1. Understanding Web Application: Definition
  2. What is a Web Application Firewall (WAF)?
  3. Web Application Firewall Types
  4. How Does Web Application Firewall Work?
  5. Importance of Web Application Firewall
  6. Advantages of Web Application Firewall

1. Understanding Web Application: Definition

The web application definition says that it is a client program that is responsible for utilizing web browsers and web technology for performing tasks over the internet. Now, since we have understood what a web application is, let us now understand what WAF is.

2. What is a Web Application Firewall (WAF)?

What is WAF? The WAF full form is a Web Application Firewall. We can define a Web Application Firewall (WAF) as a particular type of web application meant for security purposes. Companies use the WAF firewalls as a security solution to protect web applications and other internet applications from getting compromised.

While sending and receiving information using HTTP in the client-server architecture, Web Application Firewall can identify, filter, and block malicious traffic on the world wide web from arriving into the web application. Denial of Service (DoS) is one of the prevalent attack vectors that Web Application Firewall can restrict from happening. Now since you have understood the Web Application Firewall meaning, let us now understand the different types of Web Application Firewalls.

3. Web Application Firewall Types

There are three different types of Web Application Firewalls. These are:

  • Network-based WAFs: These are hardware-based firewalls that are associated locally with the web application as close as possible. The Network-based WAF vendors allow replication of rules, set across multiple appliances. This setting aids in deploying and configuring these firewalls at a large-scale. But the network-based WAFs are costly as compared to other WAF firewalls.
  • Host-based WAFs: We can integrate these types of WAFs within the code of the application itself. It makes the implementation cheaper and leverages more customization options. Due to its integration, its execution speed is more but requires local libraries along with local server resources to operate efficiently.
  • Cloud-based WAFs: Modern enterprises and organizations and enterprises depend extensively on cloud-based services. Web Application Firewalls also provide a cloud-based, low-cost solution for organizations. Other companies can provide web application security using cloud-based WAFs because they are easy to deploy and available on a subscription basis. Even the configuration of such a firewall with the web application is easy. Security administrators can change the DNS so that it can redirect its application traffic through this firewall. It will filter the web traffic through a third-party cloud-based WAF provider, keeping the web application(s) protected across a broad spectrum against application-layer attacks.

4. How Does Web Application Firewall Work?

Similar to other firewalls, WAP firewalls are hardware and software components of a network. Companies plug the hardware WAF within the existing network architecture or install the software WAF, usually accessible as a web server plugin or an inline code. In both cases, the WAF will analyze the GET and the POST request sent by the HTTPS or HTTP. Based on the organization’s policies and rules set within the firewall, it will automatically filter the malicious web traffic. Organizations also fed these web application firewalls with the top ten critical web application risks that act as a primary threat to web security. OWASP Foundation is a non-profit cyber-security organization that regularly updates such web application vulnerabilities.

Companies can configure these WAF applications to stay updated to protect web applications from those vulnerabilities. Accessing session cookies, stealing sensitive data, or rewriting content to forge information can lead to an XSS attack on the web application. Misconfiguration of servers, default passwords with poorly configured systems, gaining unauthorized access, etc. can also cause security breaches to web applications.

Organizations can easily protect themselves from all these attack vectors by configuring their Web Application Firewall by enforcing security directives, refusing insecure protocols, locking down parts of the website, only granting authentic access to trusted individuals, logging tracks, detecting ping floods, etc. Just like the way a web proxy server acts as an intermediary between the client and the server to protect the user identity – WAP operates as an intermediary like a reverse proxy. It first accepts the client request and filters out the good ones to pass it to the web application.

5. Importance of Web Application Firewall

  • Security companies provide the WAF not to protect the perimeter of a computer network but to safeguard the web application from traffic and explicitly monitor it.
  • The WAF whitelisting configuration model allows only those web traffic precisely configured and mentioned in the criteria of the filtering policy. This model proved practical for casting a wide metaphorical net to catch the potential cyber-attack.
  • Users can configure the WAF blacklisting model with some pre-identified signatures to obstruct malicious web traffic. WAF uses these signatures to detect and prevent attacks that can exploit vulnerabilities of web applications and web sites.
  • WAFs are different from traditional IDS because they are more heuristic in their working and capabilities. It means the attack surface of a web application keeps on changing as cybercriminals find new ways to compromise the system. WAFs are capable of detecting changes in the attack vector and block that unusual traffic.

6. Advantages of Web Application Firewall

Web Application Firewall protects websites and web applications from different severe attack vectors and keeps the organization’s web-assets intact. Here are some of the benefits of a web application firewall.

  • Protection against attacks: WAF can protect our web application against spams, cross-site scripting attacks, Denial of Service (DoS), Distributed Denial of Service (DDoS), and SQL injection attacks.
  • Automatic patching and scans: E-commerce websites require frequent scanning to check for vulnerabilities. WAFs can periodically scan for bugs and flaws and can patch the system with the latest bug fixes.
  • Stops Data Leakage: Applications cause data leakage when malicious actions allow the popping of error messages. Such attack vectors can lead to sensitive data leakage about the application like the server-side language used, visibility of source code or credit card numbers, version of the server in use, etc. WAFs are beneficial as they protect a web application from such data leaks.


No matter what business you are in, if you have computer systems with web applications acting as a part of your business, you must use a WAF to secure your network as well as web applications. Web Application Firewalls are affordable and effective to prevent the risk and embarrassment of an enterprise or organization. If you are interested in learning more about Cyber Security, our online Master Certificate in Cyber Security (Blue Team), India’s first program on Defensive Cyber Security, in collaboration with HackerU (Israel’s Premier Cyber Security Training Provider) can be of help!

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