Web Application Firewalls (WAF) Implementation: Best Practices
WAFs have become one of the key cornerstones of modern application security. With present-day SaaS applications owned by third-party suppliers on largely invisible infrastructure, a WAF allows for network-level visibility and control to be wrested back to the organization itself. However, implementation is one of the biggest WAF challenges, and a major responsibility.
What WAF Implementation Looks Like
After selecting a WAF tool, an organization is faced with the daunting process of implementation. In order to establish best practices, it’s important to first map out how most implementations work.
The effectiveness of a web application firewall depends heavily on how well it’s positioned, configured, managed, and monitored. The specific application will have already been selected before the buying process, and therefore will have an ideal design. A reliable way to validate your setup is by starting with a passive web application firewall deployment. In this mode, the WAF observes and logs traffic without actively blocking any requests.
From there, a WAF needs to be loaded with rules. These rules can follow a few different styles: allowlist and blocklist settings allow an organization to specify precisely which traffic sources are allowed or denied. Rate limiting is another approach, allowing policies to set thresholds on the number of requests that can be made within any one time. Geo-blocking does the same with locations: collectively, these allow a WAF to identify and block suspicious traffic. Getting to this stage demands efficient implementation.
WAF Implementation Best Practices
With WAFs becoming such cornerstones of modern security, an efficient implementation process can give organizations a major head start.
Start Secure
Before integrating any device or virtual instance into a network, it’s essential to ensure two key steps are completed: thorough documentation of the network infrastructure and proper hardening of the system being deployed.
Hardening involves applying the latest security patches and configuring the system to align with established security policies and best practices. This includes disabling unnecessary services, enforcing strong authentication controls, and securing network access. These measures help reduce the attack surface and ensure the new component doesn’t introduce vulnerabilities into the environment.
Start Small
Once your requirements are clearly defined, the next step is choosing the right application for your initial WAF deployment. For those new to Web Application Firewalls, it’s advisable to begin with a non-essential application whenever feasible. This strategy provides a safer environment to learn the ins and outs of the WAF, fine-tune its settings, and gain operational experience – all while minimizing potential disruptions to critical business operations.
It’s also wise to select an application that the security team is highly familiar with. Familiarity with normal traffic patterns enables you to more effectively monitor the impact of WAF implementation, detect anomalies, and adjust the WAF configuration best practices that are being followed.
Validate in Staging Environment
After selecting your target application, the recommended next step is to deploy your WAF in a staging environment. This setup provides a safe space to test configurations and functionality without disrupting live traffic or impacting users.
There are two common methods for creating a WAF-enabled staging environment, depending on your organization’s practices:
- Full stack replication: Duplicate the entire application infrastructure, integrating AWS WAF into the replicated stack.
- Staging via new endpoint: Introduce a new endpoint within your existing production setup. For instance, you might create a separate CloudFront distribution with an attached WAF Web ACL, which points to your current Application Load Balancer.
Once the staging environment is up and running, it’s critical to restrict access to a designated group of authorized developers. A basic way of enforcing this isolation is via IP-based restrictions, where the WAF blocks any traffic not originating from your organization’s known public IP addresses. While straightforward, this method lacks user authentication and can become cumbersome if remote access is needed – unless developers use a VPN to connect to the internal network.
Application-level authorization, on the other hand, implements authentication within the application itself, and allows the WAF to look at more general identity markers, such as the role of each user. This is a basic form of Role-Based Access Control (RBAC), and allows for a more flexible and scalable rule architecture.
Configure WAF Rules and Policies
Managed rule sets are pre-configured collections of WAF rules designed to address common web application threats such as SQL injection, cross-site scripting (XSS), and bot traffic. Offered by most WAF vendors, these rules streamline deployment and provide immediate protection.
Stress testing them is important, however – not all managed rules are going to be ideal for every application. Get it wrong, and rules can begin alerting on and outright blocking legitimate users’ traffic. A key part of rule implementation is testing their performance – which is why a staging environment is so useful. Deploying these new rules in block mode allows a security team to see precisely how those rules are interacting with an application’s traffic. This ensures your operations team becomes familiar with how WAF rules function before moving into a live environment.
When implementing within production environments, however, it’s best to enable new rules in count mode. This approach allows you to monitor rule activity and detect false positives without impacting users. Once you’re confident in the rule’s behavior, it’s possible to transition to block mode – helping avoid unintended disruptions caused by misconfigured rules.
Tweak those Rulesets
At times, even with tweaked rulesets, legitimate traffic like data in a cookie header that resembles a cross-site scripting (XSS) attempt may be mistakenly blocked by a managed rule. To address these false positives without compromising the overall effectiveness of your security posture, WAFs support further tuning: a basic example is labels, or tags, that can refine rule behavior.
When an application request aligns with a managed rule set, the WAF can then attach a label to that request. These labels persist as the request continues through the rule evaluation process, allowing it to reach custom exception rules that act on these labels. This approach allows you to bypass specific rules for traffic patterns known to be safe, and therefore reduce false positives. This is also why monitoring mode is so vital for early implementation – it’s how analysts can see which labels are applied.
Integrate WAF with Existing Security Infrastructure
Integrating WAF with security infrastructure is a critical best practice for effective implementation and ongoing security monitoring. Logs allow WAF policy choices to be integrated into other tools, and show how the WAF is interacting with incoming traffic – highlighting blocked requests, rule matches, anomalies, and potential attack patterns. Without this insight, monitoring WAF performance is far more difficult.
Integrating WAF logs into a Security Information and Event Management (SIEM) platform allows for broader threat analysis across the environment. Whether using a cloud-native SIEM or a third-party solution, feeding WAF data into this system ensures that external-facing applications are included in security investigations and incident response workflows.
Choose Easy Implementation with Check Point CloudGuard
Check Point’s cloud-based WAF – CloudGuard – intelligently learns application structures and behaviors, automatically enforcing data protection policies and content rules around it. To achieve this, CloudGuard applies two layers of artificial intelligence to all requests, one assessing the request’s associated APIs, and the other comparing each request against the application’s baseline of usual behavior. Read more about Check Point WAF with our solution brief. Implementation is made super-simple, as the WAF is based on WAF-as-a-Service architecture. As it doesn’t demand heavy agent integration, CloudGuard offers rapid routing after a one-time DNS configuration.
