Web Application Firewall: A Crucial Element to Your Cybersecurity Success

Posted on

Many businesses deliver applications to staff and customers via a web browser. Like other aspects of the modern IT infrastructure stack, cybercriminals target web applications looking for vulnerabilities to exploit. Deploying Web Application Firewalls (WAFs) can mitigate these vulnerabilities by providing a robust layer of defense for your web applications.

Defending organizations in the current threat landscape requires a robust cyber defense strategy. This strategy should include many security solutions deployed at appropriate points across the IT infrastructure. Examples include network firewalls, intrusion detection systems, network detection and response (NDR) solutions, Security Event and Information (SEIM) systems, Identity and Authentication Management (IAM), Zero Trust Network Access (ZTNA) and more. Any organization using web applications needs to deploy WAFs.

In this blog, we’ll outline what a WAF delivers and what you should look for and consider when choosing a WAF solution. In the final section, we’ll link to an overview of the add-on optional WAF install available for Progress Kemp LoadMaster load balancers. You can find out more and try it for yourself.

Importance of WAFs

A WAF augments the security protection provided by other security solutions but does not replace traditional network firewalls. It operates at various layers of the network stack, including the application, transport and network layers.

WAFs are a critical component of modern multi-layered defenses because they provide the following:

  • Defense for web applications - Businesses and other organizations depend on web applications for critical operations and customer engagement, making them prime targets for cyberattacks. WAFs act as a frontline defense, sitting directly in the web traffic path between endpoint devices and web application servers, looking for security issues in the traffic before it can reach the applications.
  • Security that goes beyond traditional defenses – WAFs analyze how web traffic using HTTP/HTTPS protocols works and inspect these network packets to look for threats. This means that WAFs can prevent threat exploits that tools like network firewalls can’t detect. It’s worth repeating that WAFs do not replace traditional network firewalls. It augments them (and other security tools) by adding additional security inspections and checking network traffic in a different and complementary way.

Common Threats Addressed by WAFs

WAFs typically come with preconfigured rules and configuration settings to mitigate common attack methods. Most WAFs can receive frequent updates on these rules to deliver protection against newly discovered threats. You should set your WAF to update its rules as often as possible.

The OWASP Core Ruleset comprises a common set of rules that WAFs based on the ModSecurity WAF Engine include. It detects and protects against the threats in the OWASP Top 10, plus many other known threats.

Examples of malicious actions that WAFs protect apps from via rules and other configuration files include:

  • Cookie tampering - Cookies are used in authentication and authorization processes to track and maintain state across HTTP sessions. By injecting malicious values into them, cookies can be used in many attacks such as SQL injection, XSS and buffer overflow.
  • Cross-site request forgery - Cross-site request forgery (CSRF or XSRF) attacks execute unwanted commands on a web application. These exploits inherit the user’s authorization level and appear legitimate to the application to which the user is authenticated. By checking referrer headers, a WAF blocks CSRF attacks.
  • Injection attacks – Injection attacks involve hijacking client sessions to insert input data into a traffic stream attackers can use to read privileged data, modify the data and execute administrative operations. A WAF mitigates such attacks by dynamically monitoring client traffic flows for malicious injection patterns and preventing unauthorized execution.
  • Cross-site scripting (XSS) - XSS attacks exploit web-based applications by sending scripts transparently activated by clients when loaded. These attacks allow for user identity theft, cookie poisoning and malicious redirection. A WAF mitigates this attack by disallowing the malicious injection of untrusted data into passed values.
  • Data Loss Prevention (DLP) - The unauthorized transfer of sensitive information from a network may happen through malicious or accidental means. A WAF minimizes the malicious or unintentional transfer of sensitive information from applications by inspecting, and then denying, egress traffic containing unauthorized data.
  • Broken authentication and session management – A WAF helps protect against the malicious use of weak session IDs and authentication methods.
  • Buffer overflow protection – A WAF can prevent user-invoked buffer overflow attacks.
  • Access control – A WAF can enforce proper access controls on application resources to prevent unauthorized use.
  • Security misconfiguration – A WAF performs continuous protection monitoring to detect and prevent access due to misconfigured security settings.
  • Real-time protection – A WAF provides continuous monitoring for known and emerging threats via rule updates.
  • Denial of service protection - A WAF can detect HTTP traffic patterns that indicate a Denial of Service (DoS) or Distributed DoS (DDoS) attack.
  • Botnet attack protection – A WAF can detect patterns from distributed botnet-based DDoS attacks and prevent them from overloading application servers.
  • Web-based malware protection – A WAF can detect and block malware attacks that use web-based attack methods.
  • Block zero-day threats – This is malicious activity detection and blocking. A WAF can help prevent zero-day vulnerabilities from being exploited before they are added to the available rulesets of known attacks.
  • Web scraping - A WAF can prevent the automated extraction of data from web applications.

Key Features of a Successful Web Application Firewall

A WAF should be able to provide thorough protection without compromising the performance of web applications. A practical and successful WAF should offer the following features.

  • Efficient threat detection - The WAF should be able to detect known attack patterns in network traffic, including encrypted TLS/SSL traffic. Anomalous network traffic should also trigger a response from the WAF to enable the detection of activities that the WAF rules may not include yet. Both allow lists and deny lists should be available. Many WAFs also have API protection features that help thwart attacks that target APIs. WAFs should also be able to spot network bot activity and block traffic from automated attack bots looking to use denial of service attacks and other methods.
  • Accuracy should be paramount - The WAF should not issue many false positive alerts or disrupt the flow of legitimate network traffic. Also, the WAF should be easy to customize to set the detection sensitivity for specific instances and applications.
  • Flexibility - The available deployment models should be flexible and support an organization’s infrastructure deployment. The WAF should be available as a hardware device, bare metal install, virtual machine or container. Deployment should support on-premises, cloud and hybrid models.
  • Easy management - The WAF should have a simple management interface that makes configuration and updating easy without sacrificing any of the security features. Real-time monitoring and alerting about any discovered issues should be easy to understand at a glance, plus it should provide the ability to analyze reported issues more deeply. There should be thorough reporting functionality or the ability to send data to another reporting tool (for example, to a SIEM solution).
  • High performance - The WAF should handle high traffic volumes without introducing bottlenecks or slowing connection sessions between endpoint devices and web applications. It should also handle unexpected spikes in traffic volumes without performance degradation. Automatic scaling of available WAF instances is a typical way to handle spikes in traffic.
  • TLS/SSL offloading - As mentioned above, the WAF needs to be able to decrypt TLS/SSL traffic to check for suspicious activity. In addition, most WAFs can offload encrypting and decrypting network traffic from application servers. Encryption services have a significant overhead and offloading them from the application server onto the WAF frees up capacity on the back-end servers.
  • Easy to integrate - The WAF should be easy to integrate with your other cybersecurity solutions and IT infrastructure. Many WAFs already integrate with load balancers, as it makes sense from a logical and physical network perspective to deploy load balancing and WAF functionality as a combined package for applications. The WAF should also be able to integrate with SIEM and security reporting tools to feed information into a big-picture view of the network and threat landscape.

Implementation Strategies

Implementing a WAF requires several key steps to deliver the security and required functionalities.

It’s crucial to assess the specific security requirements of the web application for which the WAF will be handling access requests. Then, select a WAF that aligns with those needs, either as a solution in the cloud or on-premises. The initial deployment should focus on configuring the WAF to mitigate threats without disrupting network traffic flow. Look for preconfigured templates and rulesets applicable to your application’s needs that you can download and use for the correct configuration.

Finally, frequent testing and rule updates are essential to cover new threats and maintain optimal protection levels.

Best Practices for Web Application Firewall Configuration

Configuring a WAF requires a strategic approach to deliver effective protection without impeding legitimate traffic. The best way to achieve this is by following a set of best practices.

First, define allowed traffic patterns, which will help reduce the attack surface. Second, use rulesets and tested configuration templates to block known threats. Third, frequently update the rulesets to stay ahead of evolving threats. Finally, continuous monitoring is crucial for identifying potential security incidents and updating WAF settings based on observed traffic patterns and threats.

By following these best practices, you can optimize your WAF and protect your web application from potential threats.

Role of WAFs in Enterprise-Level Cybersecurity Strategy

WAFs play a crucial role in a complete cybersecurity strategy. Integrating WAFs with other security measures creates a multi-layered defense mechanism that addresses a broad range of cyber threats.

As previously outlined, WAFs should work alongside a wide range of other cybersecurity protection solutions and techniques, such as network firewalls, intrusion detection systems, network detection and response solutions, SEIM systems, IAM, ZTNA and more.

Organizations are better protected when they adopt a layered approach because if one protective solution is compromised, others are in place to defend systems, including their web applications, from malicious attackers.

Case Studies: Successful WAF Implementations

Many organizations have deployed WAFs as integral parts of their multi-layered cyber defense strategies. We’ll highlight one success story in which LoadMaster, with the WAF component deployed, played a significant role in the security of Dell Technologies Multi-Cloud Demo Center.

The Dell Technologies Demo Center needed to increase its defenses from application layer attacks while maintaining availability to all staff, customers and partners worldwide. They chose LoadMaster and its WAF after evaluating available solutions. They selected the LoadMaster solution because it provided continuous protection against vulnerabilities with daily rule updates based on threat intelligence and research from Trustwave.

In addition to the WAF features, Dell picked LoadMaster because it combined WAF protection with other application delivery services, including intelligent load balancing, intrusion detection and prevention, edge security and authentication for broad and highly available application delivery. Read more about why Dell selected the LoadMaster Web Application Firewall on our case studies page.

The Dell success story is not an isolated example—many other organizations have improved their security by successfully deploying WAFs. Numerous stories showcase how WAFs can help you safeguard against advanced cyberattacks, decrease the chances of data breaches and deliver steady access to web services. By analyzing these examples, businesses can learn about effective deployment and management strategies for WAFs, gain valuable insights into best practices and feed lessons learned and best practices into their WAF implementation strategies.

Future Trends in Web Application Firewalls

The future of WAFs will likely include the addition of emerging technologies like machine learning and the integration of WAFs into advanced workflows as part of DevSecOps and Kubernetes. Advancements promise to enhance a WAF's capability to detect and respond to threats in real time, adapt to evolving attack patterns and provide greater transparency in web traffic analysis.


WAFs are crucial for modern web security, providing robust protection against a variety of cyber threats. To enhance web application security, businesses need to understand their importance, implement them strategically and adhere to best practices for configuration and maintenance. As cyber threats evolve, deploying WAFs should be a core part of your extensive cybersecurity measures.

WAF with LoadMaster

This blog champions implementing carefully configured WAFs within your broader cybersecurity strategy. Progress LoadMaster has a WAF based on the ModSecurity engine, an industry-leading component. It is backed by open-source rulesets and a Trustwave SpiderLabs commercial rule subscription service.

LoadMaster WAF takes advantage of all the benefits of the flexible licensing models available. Deploying LoadMaster instances with WAF via our Metered Licensing allows WAF placement to help you meet your organization’s unique application delivery and security needs.

For more information or to start a 30-day free trial of LoadMaster, including the WAF component, visit the WAF webpage.

Posted on

Doug Barney

Doug Barney was the founding editor of Redmond Magazine, Redmond Channel Partner, Redmond Developer News and Virtualization Review. Doug has also served as Executive Editor of Network World, Editor in Chief of AmigaWorld and Editor in Chief of Network Computing.