Data Security

How Web Application Firewall (WAF) protects your website

Why a Web application firewall is a vital tool to keep websites safe from cyber attacks.

A Web Application Firewall, also sometimes referred to simply as a WAF, can protect websites by monitoring and filtering HTTP traffic between the internet and the website.

A WAF can prevent websites from being attacked by the likes of cross-site request forgery (CSRF), Local File Inclusion (LFI), SQL injection, cross-site scripting (XSS), and more.

A Web Application Firewall is intended to defend purely against layer 7 application-level attacks.  A layer7 attack targets your web application directly and can be exploited with lower computing or investment by carrying a targeted attack on the application to exploit its vulnerabilities. 

When between 70% to 80% of applications have high or critical vulnerabilities waiting to be exploited, the need to combat these vulnerabilities is of vital importance. 

A business has to use a range of tools specialized at each level of the OSI (layer 3 network-level filtering and layer 7 application-level filtering) to provide a holistic defense against many different attack vectors.




Application codes and settings are never going to be completely perfect, so it is important to ensure that data is protected from the distributed denial of service (DDoS) attacks, hackers, bad bots and spammers, and most importantly against vulnerabilities and business logic flaws already present in the application.

How It Works

A Web Application Firewall sits between the client and the internet services they want to be connected to, with the WAF checking those connections as they are routed to it first.

One of the most common prevalent application attack vectors is cross-site scripting, which involves attackers injecting code which is malicious into the browser of the client to gain access to session cookies, steal confidential data, and even change content to display false information.

A Web Application Firewall can be configured to enforce Security Policy to prevent these kinds of attacks or blocks payload emanating from such attacks or prevent them at the point of exploitation attempt itself.

Misconfigured servers are another threat that a WAF can defend against. Unsafe settings like guest accounts and default passwords can often be an easy target for attackers because administrators did not follow best practices for security and created these vulnerabilities as a result.

A WAF can prevent these badly configured systems by having targeted policies in several login attempts, forcing a CAPTCHA, and rejecting protocols/ payloads that are insincere and forcing security directives.




Websites that have poor input validation can be vulnerable to code injection vulnerabilities, which sees attackers try to get SQL statements sneaked to get access to databases they are not authorized to. These attempts can be detected and blocked by a WAF.

Libraries and software that are out of date are other vulnerable areas, but a Web Application Firewall can work as a temporary solution and block these known exploits until they can be patched up.

Insufficient monitoring and logging can also result in early signs of malicious activity being overlooked, but a WAF can serve as centralized logging on point and inform administrators to the presence of any ongoing threats.

Attackers may also try to gain access to sensitive information by scanning the structure of a website and exploit any unsecured resources. A Web Application Firewall can lock down some areas of the website so that only trusted parties can gain access to them.

A WAF can also be used to prevent bot traffic by forcing a CAPTCHA challenge while implementing geo, IP, and identity-based policies from just one single entry point.

The reality is that sites are being hacked every day of the week with one study suggesting that the average is an attack as often as every 39 seconds. Of course, an attack does not necessarily equate to a successful hack, and it is the job of Web Application Firewalls to ensure they are not. 




The most common types of application attacks include SQ Injection (SQI), Distributed Denial of Service (DDoS), Defacement, Malware, and Account Hijacking. SQ Injection accounts for as much as two-thirds of all Web attacks.

What are the different types of WAFs?

There are three ways in which a Web Application Firewall can be implemented – network-based, host-based, or cloud-based.

A network WAF is usually hardware-based, cutting down on latency because of their local installation but this also the most expensive method of implementation and means that physical equipment has to be stored and maintained and has to be provisioned for peak capacity which may not always happen and is tough to predict your peak traffic upfront especially when you can have DDOS attacks.

A host WAF can be integrated completely into the software of an application. This method is much cheaper than a network WAF and is also a lot more customizable but requires intrusive touchpoints into your application for deployment.

The major downsides of a host WAF are the complex nature of its implementation, its associated maintenance costs, and the local server resources that it consumes and the management of the deployment along with the application development cycle. Maintenance costs can be especially pricey and usually need engineering time.

A cloud WAF is an option that is simple to implement in addition to being much more affordable. A cloud WAF generally provides a quick deployment that is no more complicated than changing the DNS to redirect site traffic.




A cloud WAF also costs very little in the way of upfront expenditure, with monthly and yearly fees paying for the security in the form of service and paying only for what traffic you have instead of provisioning for peak load upfront.

A cloud WAF is also able to offer a continually updated solution to ensure that new threats are protected against without any further cost or work required by the user.

The only real drawback of a cloud WAF is the necessity of a third party being handed responsibility for front-ending your traffic, and additional latency of a hop between their hosted location and your servers. 

This can be mitigated by partnering with cloud WAF vendors who have deployments in multiple regions and also provide a CDN to serve most of your content from the closest edge from where your users are visiting your site

Websites, web servers, and web applications are prime targets for cyber attackers, and a Web Application Firewall is a great form of defense. If you own an online business, you may want to consider trying we application solutions from Indusface.

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