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What is a Web Application Firewall (WAF)?

Times are changing and there is a real need for better online security for websites. Business is dependent on things being safe and secure. Tools that help achieve this security are high in demand.

A web application firewall, or WAF, is a security tool that monitors, filters, and blocks incoming and outgoing data packets from a web application or website.

It helps to protect websites and web apps from attacks by forming a barrier between a website server and client requests.

It is present on the application layer and is able to provide security and safety from a wide range of threats and dangers.

How Does a Web Application Firewall (WAF) Work?

The workings of a WAF are pretty straightforward.

In the simplest of terms, the WAF acts as an intermediary between websites and the people who want to go onto the website.

The way it works is that when a client wants to access a website, they send a request. This request is received by the website server and then the server resolves this request.

The WAF comes in between the server that hosts the web app or website and the client requests. If there are any threats, they are handled by the WAF before the client requests are forwarded to the web server.

A set of rules or policies help the WAF to ensure safety in light of the threats that a website might face.

Why is WAF Important?

Web application firewalls are essential these days. Website traffic is bound to increase and with it the threats that come along with having a website.

Hackers often rely on legitimate website visitors to make mistakes and to then capitalize on those mistakes. They are then able to exploit those users and cause harm to unsuspected parties.

WAF and other tools are used to provide a wide range of protection from these hacking threats. The end users of the website feel more secure knowing that their information is safe from harm and that there are tools and safeguards in place to protect them.

WAF and other security tools are also important for online businesses and the digital economy if we’re looking at a bigger picture. Preventing hackers from a successful hack and surveillance is key to ensuring a safer and prosperous digital economy.

Where is WAF Placed?

WAF is a useful tool, but where does it need to be placed for maximum benefit? There are different options but they depend on the use case and a broader online security vision.

The most ideal position for a WAF is to be placed behind the load balancing tier. This position is optimized for utilization (better utilization is cost effective), performance (ends the need for upstream designated WAF LB tier) and reliability (necessary for scaling the WAF) while at the same time providing security.

How do I set up WAF?

Setting up a WAF depends on a number of things. First, if you are using an appliance based WAF, then you will need to follow the accompanying instructions and make sure that the WAF is properly set up.

But most WAFs used are cloud based, meaning that you do not need to deal with physical equipment and infrastructure.

With different WAFs, the setup process can be different.

For example, if you want to enable the WAF for a GoDaddy website, then here are the following steps:

  1. Open your GoDaddy account.
  2. Go to the product page.
  3. Right next to the Website Security and Backups, click on Manage All.
  4. Next, for the domain that you want to set up the WAF for, click on the Set Up that is listed beneath Firewall.
  5. The set up process takes a few minutes if your domain name and Website Security plan are placed in the same GoDaddy account.

Note that you will need to take additional steps to set up your WAF if the DNS is hosted in a different account. This concludes the set up process for GoDaddy.

But if you are looking to use something like AWS to host your WAF, then the set up steps can look something like this:

  1. Set up AWS WAF.

You will need an AWS account for this step. Additionally, you will also need to create an IAM user via the Setting up option.

  1. Create a Web access control list.

This step is all about blocking and allowing access to your website. If you feel a particular IP should not be allowed then you can blacklist it here.

  1. Add string match rule.

A string rule match determines strings that you would want the AWS WAF to search for in a request.

  1. Add AWS Managed Rules rule group.

AWS Managed Rules provide a set of rules for the AWS WAF that are free to use and can be added in this step.

  1. Complete Web ACL configuration.

In this step, you will be finishing up the Web ACL configuration process. This will include prioritizing the rules of the WAF and managing settings like tagging, metrics and logging.

  1. Clean your resources.

In this step you will need to delete the resources that you were using after creating the AWS WAF object or else you will be charged for these services.

Other cloud based WAFs may share similarities with the AWS WAF version, but obviously there will be some differences. If you understand the fundamentals of a WAF then the set up process will be completed more smoothly and without any hiccups.

Web Application Firewall Configuration

Configuring a WAF is usually done according to three security models. The kind of configuration done depends on the use case. Choosing the right sort of configuration is also essential if you want to be in compliance with HIPAA or PCI-DSS.

Here are the three security models that help configure a web application firewall:

Whitelisting Model

A whitelisting model only permits the web traffic as per explicitly specified criteria and rules. For instance, it tends to be designed to just permit HTTP GET demands from certain IP addresses.

The whitelisting model can be pretty useful for catching a lot of malicious traffic. But unfortunately, a lot of legitimate traffic can be denied through this model. So, that’s something that you will need to keep in mind.

Whitelisting model firewalls are most likely best for web apps that are intended to be utilized by just a restricted group of individuals on a smaller network.

Blacklisting Model

A blacklisting model uses pre-set marks to obstruct web traffic that is openly malevolent, and signatures intended to prevent cyber attacks that can exploit certain sites and web applications shortcomings and weaknesses.

Blacklisting model WAFs are a great choice for websites and web apps on the public web, on the grounds that those sites can get a ton of real web traffic from new customer machines.

By blacklisting commonly known spam IPs you can blacklist them and prevent those IPs from accessing your site. Stop forum spam is a platform that you can use to find the kind of IPs that are malicious and may end up causing you harm.

Hybrid Security Model

A hybrid security model, as the name suggests, is a combination of both the whitelisting model and the blacklisting model. It takes certain things from the whitelisting model as well as the blacklisting model to get the best that the two models have to offer.

The use cases for the hybrid security model depends on the particular environment that the model is to be used in, but it can prove to be the right choice if conditions are right.

What are the Benefits of WAF?

Online businesses and websites need to make sure that they are ensuring security.

WAF helps secure your website and brings a lot of benefit to web apps that choose to employ it.

Here are some of the key benefits of WAF:

  • Prevents hacking attempts and cyber attacks: WAF helps secure your web app from cyber attacks. In this day and age, people and organizations are at risk at all times. To ensure that your site is secure, you will need to employ tools like WAF that can prevent hackers from gaining access to your website information, exposing vulnerabilities and putting your audience at harm.
  • Protects customer data: Online security is essential if you want to protect your customers. In case of a hack, not only is your website at risk and your business, but your customers can also face a lot of harm. Hackers can not only deny access to your website, but in some cases they can also capture customer information and credentials. WAF helps protect customer data by ensuring that the traffic to your website is monitored and protected.
  • Save on costs: The first thing that will help your business or web app save money is the damages you might incur incase of a cyber attack. Lengthy lawsuits and bad publicity can cause companies a fair bit of financial trouble. That being said, WAF can help you save money on resources. You will not need a professional to manually monitor traffic and to ensure that your site traffic is okay.

Attacks That WAFs Prevent

WAFs prevent attacks on an application layer level. Meaning that if a hacker is using HTTP as a means of malicious activity or entry point to do so, WAF will stand in place and act as a shield.

Here are some of the attacks that a WAF prevents:

  • Unauthorized access to protected information: Hackers can attempt to leak information that is important to the website which can include business transactions or customer information.
  • Identity theft: Identity theft is when a hacker possesses someone else to gain access to the web app and cause potential harm.
  • SQL injections: SQL injections work by targeting the database of the web app.
  • High priority data exposure: Corporate espionage favors high priority data exposure as it can render a competitors competitive advantage useless and available for all to see.
  • Fake HTTP requests: Forged HTTP requests can be made to gain access to a web app and exploit any vulnerabilities that it might have.
  • Cross site forgery: This attack targets the user of the web app and targets them to enter their credential information when they are changing their information or updating their emails on a different website.
  • Distributed Denial of Service (DDoS): DDoS attacks target a web app’s servers by overwhelming its capacity, often by using bots and other tools.

What is Cloud WAF?

A cloud WAF or a cloud-based WAF, is a web application firewall that is deployed on the cloud. Different service providers provide their cloud WAFs that are very competitive in terms of capabilities and pricing.

The main function of the cloud WAF is to act as a regular WAF meaning that it will continue to work on the application layer and ensure that the HTTP is monitored for security threats. The only difference is that it will not be relying on an appliance-based WAF.

Cloud WAF brings a number of advantages that conventional WAFs lack.


The main advantage that a cloud based WAF brings is that it is easy to use and is scalable. This means that your IT team will not have to make any hardware or software changes. Not only that, but as your website grows and scales, you can upgrade your cloud WAF to facilitate your business growth.


Cloud WAF is a cost effective solution. Mainly because you are not responsible for handling hardware and software updates, not to mention the maintenance of equipment and infrastructure.

More Secure

Additionally, cloud WAFs are more secure since one attack attempt and it’s preface can be understood by the WAF and provide greater security to everyone that uses the same cloud based WAF.

Easy to Adapt

The rules or policies that a cloud based WAF enforces are similar to that of an appliance based WAF. So, you can rest assured that you will not be compromising on security if you choose to switch over to a cloud web application firewall.

What is the difference between WAF and Firewall?

While the word firewall may be common between the two, WAF and firewalls are completely different.

Firewalls are used to protect a LAN (Local Area Network) from unauthorized access and to prevent any attacks from being carried out on the LAN.

In contrast, WAF is designed to act only on the application layer. Meaning that it uses the HTTP to facilitate the protection of the web application’s server. This is done by monitoring the client side requests and by acting as a barrier between the web app server and clients.

As businesses go online, WAF becomes essential to protect web apps from zero day threats as well as other kinds of online attacks.

Both the firewall and WAF are important for maintaining security and ensuring security is maintained.

What is the Function of a Web Application Firewall (WAF)?

The main function of a web application firewall is to act as a barrier of shield between the web app and the internet at large.

It’s main purpose is to provide security to a web app and in particular, it’s servers. WAF acts as a reverse proxy meaning that the WAF receives any requests from users directed to the web app first. It then relays this information to the web app’s servers after ensuring that the request is not malicious or harmful in any way.

The policies or in layman terms the rule set of the WAF help guide and govern the kind of traffic that is acceptable for the web application.

Here are some key functions that the WAF performs:

  • Provides a broad security mechanism.

As discussed earlier, WAF is primarily a security mechanism that is used to ensure the safety and online security of the web app.

  • Ensures policies are being followed.

The policies or set of rules that constitute the WAF ensure that the website is able to handle a variety of threats that can cause potential harm or damage to the web app or its users.

Policies and the priority set between the different rules is also a defining factor in ensuring that the WAF is performing as intended.

  • Help act as a barrier between the client and the web app’s server.

WAF provides security by putting itself in between the client requests and the web app servers. This ensures that any threats are neutralized before they are able to reach the actual server.

WAFs, especially the cloud based WAFs, have the added advantage of being updated frequently. Meaning that any new threats that are faced by websites have counters created and included in the WAFs to prevent any harm to other users.

What are WAF Rules?

WAF provides security to a website by applying a set of security rules to an HTTP conversation.

As mentioned, WAF is comprised of security rules. This means that potential threats to a website, ranging from SQL injections to DDoS attacks, forceful browsing to XML violations, all are covered by the web application firewall.

Different WAF service providers provide varying solutions and sets of rules that are used to protect servers and web applications.

Most will come with a wide range of protections. Some of the most common WAF rules to deal with attacks include:

  • Session tampering: WAF provides protection from hackers or bots that try to take control of your browsing session. These attacks usually take place when a user is entering their credit card or other sensitive information.
  • XML violations: XML violations allow the schema to accept malicious files and programs that were previously blocked by the unaltered schema.
  • SQL injections: WAF prevents hackers from entering an SQL for backend database manipulation, helping to protect business and customer data.
  • DDoS attacks: DDoS attacks take place when bots visit a website and overload the servers hosting the website. WAF monitors this sort of traffic and helps prevent suspicious traffic from accessing the website.
  • Auth attacks: Auth attacks, as the name suggests, attempt to gain access by using credentials to allow access to a web app or website.
  • JSON violations: WAF ensures that the JSON facilitating the exchange of incoming requests and data packets remains secure over the HTTPS.
  • File attacks: Uploaded files can potentially expose a number of vulnerabilities. File attacks are kept at bay through the web application firewall.
  • XSS injections: XSS injections or Cross Site Scripting injections harm other users of the web application.

What is WAF Violation?

To understand WAF violations, we need to reiterate what exactly is a web application firewall.

It is a set of rules that help to secure and protect a web application from hackers or other bad actors.

A WAF violation is anything that attempts to bypass or access the web app and cause harm.

Using an example would be the easiest way to understand a WAF violation.

Consider that you have a functioning web app that is getting a significant amount of traffic from across the globe. A hacker sees this and decides to target your website.

By using bots, they attempt to overload your website and cause discomfort to the genuine online visitors that come across your website.

A WAF will see this traffic incoming and deem it to be suspicious. It may even deem this traffic to be harmful and prevent it from accessing the web app by triggering a violation.

Any attempts or potential attacks are thwarted by the web application firewall as it will trigger violations depending on the nature of the attack.

These violations need to be monitored and if there is a rapid increase in the number of violations for a particular website, then you might want to involve cyber security professionals as you might be at risk of a full fledged online attack.

Does WAF Protect Against Malware?

WAF can definitely protect your website from malware. Given that malware has become so hard to avoid for users,

Oftentimes, hackers first target websites by understanding the kind of traffic that usually visits these websites. They passively monitor a website and then try to use tools like bots to potentially overwhelm the hosting servers.

Like other firewalls, WAF monitors the traffic that comes onto a website. If a website owner has deemed traffic from a particular source or region to be blocked, then the WAF can prevent access to the website for these visitors.

Hackers will not be able to inject malicious code using an SQL injection or conduct a DDoS (Distributed Denial of Service) attack that can potentially render a website useless or actually cause harm to the website’s visitors.

Additionally, suspicious traffic can be blocked from entering the website via WAF. Other actions that WAF can take to prevent malware attacks include preventing code to be manipulated and blocking backdoor access attempts.

But you need to understand that a WAF is not designed to protect a website from all kinds of threats. As it resides on the protocol layer in the OSI model, it generally serves as a means to provide well rounded security from a wide range of potential dangers.