Like every other type of software, web application firewalls (WAFs) are split into two fields: proprietary solutions and open-source web application firewalls that can be self-deployed. Both aim to achieve the same thing by filtering harmful traffic, and therefore preventing attackers from having direct contact with applications and websites.
A WAF is a security software that sits between your server and a user’s endpoint: this status as a gateway grants it visibility into all the traffic destined for your website. This analysis looks at a variety of indicators to determine the traffic’s legitimacy: a plethora of data points lets it investigate each packet, which then allows the WAF to determine a packet’s legitimacy. Once it has been assessed, the data packet is either forwarded to its destination, or dropped.
WAFs were once primarily offered as hardware devices that sat in front of your web server. All traffic would first go through the device for analysis, which would be conducted within the hardware. Nowadays, cloud-based WAFs allow for your web or application traffic to simply be forwarded to a central WAF analysis engine remotely. As a result, many modern WAFs can be deployed as local software: they can even be made into part of the web application itself and hosted in the same space as your website. Because cloud-based WAFs take advantage of this virtual traffic routing, it’s possible to use open source tools. These are free, publicly-available tools with accessible codebases and often far-reaching community support.
Open source WAF software offers several advantages – particularly for an organization exploring the world of cybersecurity for the first time. Here’s a breakdown of those advantages:
Open source is essentially synonymous with ‘free’, meaning most of the publicly available firewalls are highly accessible. This means there is no demand to pay for premium recurring subscriptions just to use them – and no limit on your throughput. This can be in sharp contrast to many proprietary WAF providers, who demand upfront fees, subscriptions, and who could even start dropping requests if you reach your contractual throughput limit.
Many organizations don’t enjoy the thought of sending sensitive connection data to a third-party solution: open source tools can quell some of these fears by offering a backbone of accessible code that runs locally on your own machine. It achieves this in a way that is much more efficient than building an entire solution from the ground up in-house, as well.
In addition to upfront cost savings, there’s no risk of vendor lock-in with open-source web application firewalls, which can otherwise make it challenging to switch products or providers down the line. This can ensure greater flexibility when integrating with other security and networking solutions in the future, without being restricted to the vendor’s own tools.
Another key advantage is the strong commitment of the developer community. With a large number of independent developers collaborating on the code and continuously testing it, flaws and vulnerabilities are often identified and addressed quickly – potentially even faster than proprietary software, which is more secretive. This contributes positively to the software’s quality, stability, and security, and helps your WAF stay on top of threats like SQL injection and Cross-Site Scripting.
While open source WAFs can be a fantastic introduction for small enterprises, their real-world application can sometimes place unique demands on an enterprise’s resources.
While the community spirit is what drives open source projects, it’s worth keeping in mind that certain WAF features – like deep packet inspection, bot identification, and more – are often provided in a piecemeal fashion. This can take the form of individual, developer-produced plugins – and finding the correct ensemble of features that your enterprise needs can take considerable time.
Another uncomfortable component to open-source WAFs is this exact reliance on unknown, public developers: there’s often very little oversight on bugs and exploits, and – if your WAF tool suddenly becomes no longer actively upgraded by the open source dev team – it threatens to rapidly become a piece of legacy software.
Because open source projects are so reliant on the good will of a community, the uptake of advanced WAF features (like machine learning-driven traffic analysis) is almost always slower than their tightly-maintained proprietary counterparts.
Open-source WAFs usually require extensive configuration from the outset – often demanding more effort than standard firewalls. To ensure optimal protection, a thorough understanding of both the open-source WAF and the specific application it’s being deployed on is necessary. If your team lacks this expertise, outsourcing becomes necessary, which can be costly.
Additionally, maintaining an open-source WAF is labor-intensive due to the dynamic nature of web applications, which are constantly evolving and require frequent updates to keep up with new features and security needs. Keeping false positives to a minimum demands even more work. The fast-paced app development environment, driven by creative experimentation with new technologies and trends, means that applications are continuously changing. As a result, if the WAF is part of your organization’s overall security framework, the cybersecurity team cannot design or implement features in isolation; they must adapt to these ongoing changes.
The ability for the WAF tool to prevent malicious actors from gaining access to your applications and servers is their core security offering: however, some open source WAFs can experience fail-open or fail-close events when overwhelmed by heavy traffic. In a fail-open event, the WAF switches to monitoring mode and allows all traffic through – including potentially malicious data. During a fail-close event, all traffic is blocked, which can result in a denial of service. Open source WAFs are also generally more vulnerable to other tactics to rule bypasses, such as faking request sources or using mixed-case characters to evade case-sensitive rules.
Application and web security is constantly changing: and, as the gateway to your enterprise’s sensitive resources, your WAF needs to be suitably well-provisioned. Open source tools like Check Point’s Open App-Sec offer a WAF engine that identifies novel threats with machine-learning threat identification. It adapts over time via continuous learning, reducing the constant demands of other WAF tools. Easily implement it into your own architecture with APIs or infra as code.
If you need a more structured tool, Check Point’s CloudGuard is a cutting-edge WAF with similar in-depth traffic behavioral analysis, API discovery, and greater throughput. Learn how to secure the applications you rely on with our whitepaper here – or, if you’d like to see how CloudGuard actively combats attackers – schedule a demo today.
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