Generally working as any other firewall does, a Web Application Firewall (WAF) serves as a filter between the internet and a web application, monitoring and blocking data that tries to make its way across. WAFs offer different solutions based on preference–they can either be cloud-based, network-based, or host-based. It’s location is generally in front of a web application, so that it bounces any information that’s not useful and may even be harmful to a given web application.
Through a base-line checker, the firewall checks data that tries to enter the web application for potential threats using a function that tests the logic of the data. If the data’s logic seems malicious, the firewall prevents it from entering the web application, thereby ensuring the web application remains secure and users’ data is not subject to inappropriate and even illegal use.
The Internet is full of people who want to steal information and disrupt service. Malicious actors sometimes try to destroy a functioning web application to exploit and manipulate its data for their own use. A firewall acts as guard and scans for proper identification before they let a user or data into this system, preventing bad actors from gaining entrance and keeping the most sensitive data secure for users.
A properly configured firewall goes a step beyond traditional web application security measures such as intrusion detection systems (IDSes) by offering customized inspections, thereby detecting and thus preventing extremely harmful threats from ticking off the web application. Firewalls, specifically, can be very beneficial to companies offering a service over the Internet, such as online banking software or ticketing companies.
How a Web Application Firewall Works
A firewall works to assess HTTP commands, and according to a preexisting framework, accept or reject a request based on them being either harmless or potentially malicious. The key transactions this firewall would analyze would be GET commands, that attempt to retrieve information from the web application’s server, and POST commands, that’re specific to displaying information to the user.
There are two main approaches a firewall takes to assess information, and the third can be a hybrid of these two approaches. These work as follows:
Whitelisting
The default setting for the firewall in this approach rejects all requests except only for the ones it’s familiar with. These familiar requests come from known IP addresses that can be fed into the system beforehand. This approach may use less resources than would blacklisting. A drawback to this kind of approach is that there might be harmless IPs withheld from accessing the software in the firewall’s attempt to block traffic. This approach plays it safe, casting a big margin of error through which it’s hard to move across. This makes this approach a little imprecise, but it’s the safest.
Blacklisting
On the other hand, the blacklisting approach doesn’t block incoming traffic as a default, but instead lets them enter through, and with a preprogrammed rule-based system, finds harmful software. This makes it a perfect avenue to use for public website where the website is inundated with requests, with most requests not known to be either harmful or harmless. However, this approach may use a little more than just knowing what to trust; it requires research into what type of IPs can be harmful, and an assessment of what kind of characteristics these IPs possess.
Hybrid
As the name suggests, this approach uses elements of both in protecting a web application. Really it’s a matter of your goals and specific case which approach you use and for which application.
Types of Web Application Firewalls
Network-based Web Application Firewalls
These firewalls are built to be on premise, and therefore in close proximity with the application itself. This reduces latency. The vendors that sell these types of firewalls generally allow the regeneration of rules and systems so that can be applied across a wide variety of appliances–therefore they can be deployed large-scale, can be managed and configured easily. This doesn’t come easy, though, because costs are involved first in setting up this type of system, and then maintaining it.
Host-based Web Application Firewalls
Think of a human being acting as a host to a virus; the virus uses the human body to travel, regenerate, and generally exist. In the same way, this type of firewall can be integrated into the code itself thereby living on it. Since they’re embedded into the code, these firewall types don’t incur a lot of installation costs or even maintenance costs. They’re highly customizable, too. However, the challenge lies in operating these firewalls since they depend on an application library and may have to use the local server to access resources. This puts the onus on developers, analysts and DevOps engineers to produce those resources.
Cloud-hosted Web Application Firewalls
These are the viable option for those organizations that are looking for an easy-to-deploy, cheaper option to firewalling. These require minimal resources for deployment and maintenance. Usually, you would pay a subscription fee to a vendor and the vendor does the rest. They operate by employing a DNS or a change in proxy to push away traffic not meant for the web application. It may be a difficult decision to put your web application’s security in the hands of a third-party subscription vendor, but it may provide protection across a wide variety of locations. These firewalls also come equipped with skills to detect latest security issues because of their versatility.
Benefits of Web Application Firewalls
WAFs serve to protect application data that’s being transmitted online through web applications. Sometimes a threat might bypass a traditional firewall and hit the application directly. These threats include:
- Cross-Site Scripting Attacks: These attacks enable a malicious software to enter and interact with a user’s web browser.
- Structured Query Language Injection: This is harmful for any application using an SQL database, where the database is sensitive to attacks from malicious software that can change the information contained therein.
- Web Session Hacking: The malicious user would gain access to a user’s domain and thus act as an authorized user. These users directly attack an application’s cookies, thereby stealing information.
- Distributed Denial of Service Attacks: These attacks flood a web application and suffocate it until it’s no longer able to provide service to its users. This creates downtime and can cause serious problems for businesses, as users turn to the competition and are left with a bad impression of the business in question.
A properly configured WAF, when paired with other security precautions within an organization, will address all of these threats and effectively guarantee a web application is secure and sensitive user data inaccessible to outside parties.
Why Are WAFs Necessary?
An important government agency or a banking institution has access to massive amounts of important and highly sensitive information. They have an obligation to their users to keep this data from falling into the wrong hands. In order to avoid data becoming compromised, they employ the use of firewalls. Credit card data and customer information can become of easy access to hackers if the web application is not protected behind a firewall.
There may also be consumer protection laws in place for institutions like banks. Therefore, banks use firewalls to meet those legal requirements as well.
Ideally, a WAF is used in conjunction with other firewall types such as next-generation firewalls, or IDSes. Such a combination provides a comprehensive security system and customers’ information is protected and institutions can protect themselves from expensive lawsuits that will probably go against their favor if they don’t employ firewalls.
Web Application Firewall Options
There are different WAF options available, including paid and open source. Firewall is a general term that’s used for any type of firmware that deploys the use of inspection to detect malicious data. Different types of firmware exist under the umbrella scope of the term firewall and operate differently, covering different areas. WAF is one such variation. WAF is special because it only focuses on attacks that pervade the realm of web applications. Other types of firewalls, while useful, may not be able to protect against attacks directly on sensitive websites and web applications.
A WAF may also prove useful when thinking about continuous security measures that usually take up more resources and more energy. It can prove to be a one-off solution. Attacks-in-progress can also be detected and the user alerted of potential threats thereby generating a sequence of actions that will then prevent the attack from being successful.
As web applications become more complex, so do the threats posed to them. Added complexity means your online data is more vulnerable to attacks. Firewalls serve to prevent the most sensitive information from falling into the hands of bad actors online and are in many cases essential. If you think you might need a firewall to protect your users’ data, you probably do.
In addition to providing security against potential threats, WAFs can also be necessary in terms of compliance with regulatory authorities. In turn, they can protect the business from serious customer doubt and also from potential penalties incurred if such measures aren’t taken. A bank that leaks customer information won’t be in business for very long, and WAFs play a key role in this.
