• Web Application Firewall

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Web Application Firewall (WAF)

A Web Application Firewall (WAF) helps protect web applications by filtering and monitoring HTTP traffic between a web application and the Internet. It typically protects web applications from attacks such as cross-site forgery, cross-site-scripting (XSS), file inclusion, SQL injection, and others. A WAF is a layer 7 defense protocol (in the OSI model), and is not designed to defend against all types of attacks. This method of attack mitigation is usually part of a suite of tools to create a holistic defense against a range of attacks.

By deploying a WAF in front of a web application, a shield is placed between the web application and the Internet. While a proxy server protects a client machine’s identity by using an intermediary, a WAF is a type of reverse-proxy, protecting the server from exposure by having clients pass through the WAF before reaching the server.

A WAF operates through a set of rules often called policies. These policies aim to protect against vulnerabilities in the application by filtering out malicious traffic. The value of a WAF comes in part from the speed and ease with which policy modifications can be implemented, allowing for faster response to various attack vectors; during a DDoS attack, rate limiting can be quickly implemented by modifying WAF policies.

1 %

92% of reported vulnerabilities are in applications, not networks

1 %

62% of companies are not confident about their application security

Types of WAF:





A hardware-based WAF is a hardware that is installed locally within the local area network (LAN) close to the web and application servers. An operating system runs within the appliance, supporting software configurations and updates.

A software-based WAF is installed on a virtual machine (VM) instead of a physical hardware appliance. All WAF components are essentially the same as a hardware WAF. The only difference is that users would need to have their own hypervisor to run the virtual machine.

A cloud-based WAF is a newer generation of WAF that is provided and managed directly by a service provider in the form of software-as-a-service (SaaS). Unlike software-based WAF, here the WAF components are entirely located on the cloud, so that the user does not have to install anything, neither locally nor on a virtual machine.

What is it?

The greatest advantage of a hardware-based WAF is fast speed and high performance. Due to its physical proximity to the server, it tracks and filters data packets to and from the website with very low latency. The major downside is that owning and maintaining hardware machines is not cheap. From acquisition and installation to storage and maintenance, hardware-based WAFs are associated with higher costs compared to other types of WAFs

The main advantage of a software-based WAF is flexibility. Not only can it be used within an on-premises system, the virtual machine can also be deployed in the cloud, connecting to cloud-based web and application servers. A software WAF is also a cheaper option compared to hardware WAFs. However, the major downside is that since it runs on a virtual machine, higher latency is expected during monitoring and filtering processes, making it a little slower than hardware WAFs.

The major advantage of cloud-based WAF is simplicity. The user does not need to install any software physically and only needs to enroll in a subscription plan. The service provider provides all the optimization and updates, so that the user does not need to manage the WAF by themselves. On the other hand, the disadvantage is that since the WAF is entirely managed by the service provider, there is not much room for customization.

Suitable for who?

A hardware-based WAF is commonly used by large companies who gain hundreds of thousands of visits on a daily basis. This is because hardware-based WAF is suitable to handle a massive amount of clients efficiently and at speed when performance is the highest priority. Besides, most large businesses can easily afford the managing and operating costs of running the hardware.

Clearly, software WAFs are commonly used for companies with web and application servers based in the cloud, such as data centers and hosting providers. They are also popular among small and medium-sized enterprises who need to protect their web applications at lower costs.

Cloud-based WAFs are suitable for most small and medium-sized companies, since they do not require physical storage place and manual maintenance. These are great for companies without extra resources to manage a WAF.

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