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Comparing Azure Firewall, Azure WAF, and open-appsec WAF

Web applications form a key part of many modern businesses, but they are also a common target for cyber attacks. As a result, organizations need to implement security measures to protect their web applications from potential threats.

Microsoft Azure provides several options for web application security, including Azure WAF and Azure Firewall, while open-appsec WAF is a new and open-source alternative. However, it may not be easy to figure out which solutions best suit your organization's needs.

In this article, we will talk about the differences between Azure WAF, Azure Firewall, and the open-appsec WAF to help you decide which solution to choose for your business. We will explore the features and capabilities of each solution, as well as their advantages and disadvantages, giving you a comprehensive understanding of how they differ and which one may be best for your organization.

Difference Between Azure Firewall, Azure WAF, and open-appsec WAF

Differentiating Factors

Azure Firewall

Azure WAF

open-appsec WAF

Intrusion Prevention System Used

Uses signature-based intrusion detection and prevention system

Not Available

Uses Snort 3.0 engine

Type of System Configuration Used

Not Available

Not Available

Declarative Configuration and WebUI (SaaS)

System Maintenance Complexity

Uses a signature-based network security approach, so there’s complex system maintenance

Has a complex system maintenance procedure because of its rules, policies, and exclusion list

Provides easy system maintenance due to the absence of threat signatures, rules, and exceptions to protect your web app

Exclusive Web Application Protection

Needs an additional Azure service to protect web applications against attacks effectively

Effectively protects your Azure-based web app from attacks without needing any extra security services or tools

Acts as a standalone web application security service and can protect all web applications irrespective of where they are hosted

Free Version

No Free Trial

No Free Trial

Is free and also has a paid Premium version


Pricing is based on two main factors: the deployment and the amount of data processed

Pricing depends on the volume of traffic your web application receives

Is free and also offers pay-as-you-go pricing in its premium edition

Malicious Bot Prevention

Doesn't offer an exclusive feature that protects against malicious bot attacks

Uses the managed bot protection rule to hinder any efforts by malicious bots to evade your web applications

To identify malicious bots, it employs machine learning models that compare incoming requests with characteristics of known malicious bots and legitimate user behavior


Not open-source

Not open-source

Is open-source, and a third party has independently verified its source code

Web Latency

Few cases of increased web latency

Doesn’t increase web latency

No instances of increased web latency

False Positives

Few false positives

Sometimes detects false positives

Strongly reduced cases of false positives

Zero-Day Detection

Uses Microsoft Cyber Security’s threat intelligence and signature-based Intrusion detection and prevention system to protect your Azure resources against zero-day attacks

Lacks a robust feature that protects your web application against zero-day attacks

Uses machine learning models, threat prevention techniques, and the Snort 3.0 Intrusion Prevention System to identify and thwart zero-day attacks

WAF Community and Customer Service

Has a large community and readily available resources

Has a large community of users

Has a medium-sized user community

Machine-Learning App Security Approach

Not Available

Not Available

Uses two machine learning models (offline and online) to secure your web apps and web APIs

Azure Firewall Review

This cloud security solution offers comprehensive data, resources, and access protection to all Azure environments. When deployed, it uses signatures, real-time updates, and threat intelligence to monitor all incoming and outgoing traffic, alert you, filter out malicious ones, and suggest possible mitigation solutions.

You can manage the Azure Firewall via the Azure Monitor (for single accounts) and Azure Firewall Manager (if you're managing multiple accounts).

Azure Firewall is subdivided into three categories, Azure Standard, Azure Premium, and Azure Basic (preview). Each of these has been explained below.

Azure Firewall Standard

The Azure Firewall Standard provides layers 3, 4, 5, 6, and 7 protections to your Azure resources. It monitors traffic, filters out malicious attacks, alerts you, and suggests possible solutions. It does this through its integration with Microsoft Cyber Security to provide the threat intelligence it needs to identify malicious traffic. Note that Microsoft Cyber Security is continuously updated in real-time to help Azure Firewall identify traits of unknown exploits.

Azure Firewall Premium

This Azure Firewall Premium version includes all the features of the Azure Firewall Standard. In addition, Azure Firewall Premium offers a signature-based Intrusion Prevention System (IPS) to protect against unknown vulnerabilities. It has over 58,000 unique signatures spanning over 50 exploit categories, including malware, phishing, coin mining, and trojan attacks.

Azure Firewall Basic (Preview)

Azure Firewall Basic is intended for small and medium size (SMB) customers. It provides the essential protection SMB customers need at an affordable price point. Azure Firewall Basic is similar to Firewall Standard, but has the following main limitations:

  • Supports Threat Intel alert mode only

  • Fixed scale unit to run the service on two virtual machine backend instances

  • Recommended for environments with an estimated throughput of 250 Mbps

Pros and Cons of Azure Firewall



The combination of threat intelligence and signature-based IDP system makes it an effective security solution against web attacks.

It protects only Microsoft Azure environments.

It offers effective network monitoring and filtering.

It doesn’t provide comprehensive protection for web applications.

It has unrestricted cloud scalability to monitor all traffic, even at peak times.

There’s complex system maintenance due to signature handling.

It is cost-effective.

It is easy to configure its blacklist, whitelist, and Fully Qualified Domain Name (FQDN) lists.

Azure WAF Review

The developers of the Azure WAF know that attackers start probing your app for vulnerabilities the minute it goes live. The first option would be to protect your app by configuring security measures into its code during development; however, this option is rigorous and requires constant maintenance.

To help solve this, the Azure security team developed a WAF to protect your application without changing its topography. The Azure WAF is fast and easy to deploy. It provides centralized protection against many common web attacks like the following:

  • SQL Injection

  • Cross Site Scripting (XSS)

  • Request Smuggling

  • Local and Remote File Inclusion

It is a cloud-based security solution and works effectively to protect all Azure-hosted web applications and environments, including Azure Application Gateway, Azure Front Door, Azure Content Delivery Network, etc.

Furthermore, Azure WAF uses rules, exclusion lists, and policies to detect and filter out malicious requests. Its rules are divided into managed rules (created by the Azure security team and cannot be deleted) and custom rules (that you can create to help tailor your app's security). Policies, on the other hand, are a combination of (managed and custom) rules, exclusion lists, and other Azure WAF settings that offer advanced web application security.

Additionally, the Azure Web Application Firewall can protect multiple web applications simultaneously and can be configured to detect malicious traffic, block it, or both.

Pros and Cons of Azure WAF



It is easy to deploy.

Its exclusion list is difficult to manage.

It doesn't increase web latency because It carries out identity validation and load balancing simultaneously.

There are some cases of false positives.

It can be used to protect multiple apps simultaneously.

It has a friendly user interface.

open-appsec WAF Review

Are you looking for a way to block attacks on your web application before they happen? So look no further, as open-appsec uses machine learning to continuously detect and preemptively block threats before they can do any damage. Its code has also been published on GitHub, and the effectiveness of its WAF has been successfully proven in numerous tests by third parties. Try open-appsec in the Playground today.

The open-appsec WAF is an open-source WAF designed to defend web applications against common web attacks, OWASP Top 10 threats, and zero-day attacks, including Log4Shell, Text4Shell, and Spring4Shell. It uses machine learning models to discover vulnerabilities and exploits in incoming and outgoing web requests.

This web application firewall is compatible with popular DevOps environments like NGINX, Kubernetes, and Envoy, making it simple to use, install, and manage. It is cloud-based and employs infrastructure-as-code and declarative APIs for ease of use.

Furthermore, the traditional approach for web application protection is the use of predefined signatures. This approach can effectively prevent well-known attacks but may fail to detect unknown vulnerabilities. To mitigate this, some WAFs broaden their signature scope, often leading to a higher rate of false positives. In contrast, reducing the bandwidth of their signatures would increase the chances of false negatives. The open-appsec WAF solves this problem by utilizing two machine learning models, allowing it to detect known and unknown attacks more efficiently and accurately.

The first machine learning model used in the open-appsec WAF is an offline supervised model. It analyzes incoming requests and assigns them a threat score based on their match with known malicious indicators. The data used to make these assessments is sourced from a vast collection of requests from all over the world, both malicious and benign. If a request is considered safe, it will be granted access to the web application, but if it is deemed malicious, it will be passed on to the second machine learning model used by the open-appsec WAF.

The second machine learning model used by the open-appsec WAF operates in real-time and is unsupervised. It evaluates suspicious requests by analyzing various factors related to the structure of your application and user behavior, such as the following:

  • User’s Reputation Score

  • Payload Score

  • URL

  • Parameters

Based on this evaluation, the model either blocks the request or allows it access to your web application. This unsupervised, online model aims to minimize the occurrence of false positive results.

Features of open-appsec

  1. ML Threat Prevention

  2. Integration with Kubernetes, NGINX, NGINX Ingress, etc.

  3. API Security

  4. Intrusion Prevention

  5. Real-time Data Logs and Analytics

Pros and Cons of open-appsec WAF



It makes system maintenance simple due to the absence of exception handling, rules, and threat signatures.

It has a small community.

It has a free version.

It is a fairly new WAF.

It offers preemptive protection against attacks.

It is open-source.

It effectively protects web applications against unknown attacks.

It has multiple integrations.

It uses a declarative system configuration to declare actions and outcomes.


The choice between these solutions will depend on the specific security needs of your organization. The Azure WAF is the best choice to protect all your Azure-hosted web applications, and Azure Firewall is the best network security solution to protect all the data and resources in your Azure environment.

However, open-appsec WAF stands out as it is open-source, allowing you to explore and analyze how it works before having to pay (that is if you want technical support). It also uses machine-learning models to protect your web applications in advance.

Try open-appsec in the Playground today.

Frequently Asked Questions

What is the difference between the Azure Application Gateway and Azure WAF?

The Azure Application Gateway is a load balancer that helps you to manage traffic to your Azure-hosted web applications. It provides layer 7 routing and load balancing capabilities, allowing you to distribute incoming traffic across multiple backend servers based on the rules you define.

On the other hand, Azure WAF is a cloud-based, firewall-as-a-service solution that protects your web applications against a wide range of web attacks, including SQLi, XSS, OWASP Top 10 attacks, and other malicious traffic.

Is Azure WAF a load balancer?

No, Azure WAF is not a load balancer. It is a security solution that protects your web applications against various web-based attacks.

What layer is Azure Firewall?

The Azure Firewall operates from layers 3 to 7 of the Open Systems Interconnection (OSI) model. This means that Azure Firewall provides security for network traffic based on the source and destination IP addresses, port numbers, and protocol types of the traffic.


Experiment with open-appsec for Linux, Kubernetes or Kong using a free virtual lab

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