RESTful Api spec is important in WAF




What is WAF?

WAF stands for Web Application Firewall. It is a security solution designed to protect web applications from various online threats, vulnerabilities, and attacks. A WAF acts as a barrier between a web application and the external world, filtering and monitoring incoming and outgoing traffic to detect and prevent malicious activities.

The primary purpose of a WAF is to safeguard web applications from common attacks such as:

  • SQL Injection: Attackers attempt to insert malicious SQL queries into input fields to manipulate or gain unauthorized access to a database.

  • Cross-Site Scripting (XSS): Malicious scripts are injected into web pages, which can lead to the theft of user data or session hijacking.

  • Cross-Site Request Forgery (CSRF): Attackers trick users into performing actions they did not intend, often leading to unauthorized actions being taken on a web application.

  • Application-layer DDoS attacks: Attackers flood the web application with a high volume of requests, overwhelming its resources and causing it to become unavailable.

  • Brute-force attacks: Repeated attempts to guess passwords or credentials to gain unauthorized access to the application.

  • File inclusion attacks: Unauthorized inclusion of files, often used to gain access to sensitive files or execute malicious code.

A WAF operates by analyzing incoming HTTP and HTTPS requests, examining their contents for suspicious patterns, and blocking or allowing them based on a set of predefined security rules. Some WAFs use signature-based detection, while others employ behavioral analysis and machine learning to identify and mitigate threats.

WAFs can be implemented as hardware appliances, software solutions, or cloud-based services, and they play a crucial role in maintaining the security and integrity of web applications, particularly in today's digital landscape where online threats are constantly evolving.

How does a WAF work?

A Web Application Firewall (WAF) works by monitoring, filtering, and controlling the traffic between a web application and its users. It is designed to identify and prevent various types of cyberattacks and vulnerabilities that target web applications. Here's how a WAF typically works:

  • Traffic Inspection: When a user interacts with a web application by sending an HTTP request (e.g., accessing a webpage, submitting a form), the WAF intercepts and inspects the incoming traffic before it reaches the web server.

  • HTTP Parsing: The WAF parses the HTTP request to understand its components, such as the request method, headers, URL, query parameters, and request body.

  • Rule-based Filtering: The WAF applies a set of predefined security rules to the parsed request. These rules define patterns of known attacks or vulnerabilities, such as SQL injection, cross-site scripting (XSS), and more. If the WAF detects any match between the request content and these rules, it takes action to mitigate the threat.

  • Blocking or Allowing Traffic: Based on the rule evaluation, the WAF decides whether to allow the request to proceed to the web application or to block it. If the request is deemed malicious or suspicious, the WAF can block it and prevent it from reaching the web server.

  • Response Analysis: The WAF also inspects the web application's responses to outgoing requests. It can detect and prevent sensitive information leakage or data exposure in the application's responses.

  • Learning and Adaptation: Some modern WAFs employ machine learning and behavioral analysis techniques to identify new and evolving threats. These systems can learn the normal behavior of an application over time and detect anomalies that may indicate an attack.

  • Custom Rules: Administrators can often configure custom rules to suit the specific security needs of their web application. This allows them to address application-specific vulnerabilities and potential threats.

  • Logging and Reporting: WAFs generate logs and reports about detected threats, suspicious activities, and blocked requests. This information helps administrators analyze the security posture of their web application and fine-tune the WAF's rules if necessary.

  • Continuous Monitoring: WAFs provide ongoing protection by continuously monitoring and filtering traffic, adapting to emerging threats, and maintaining the security of the web application.

It's important to note that while a WAF is a valuable security layer, it is not a comprehensive solution on its own. A combination of security measures, including secure coding practices, regular security assessments, and patch management, is essential to ensure the overall security of web applications.

A RESTful Api Spec is important for a WAF custom rule.

How do we config the custom rule in a WAF? There are two main ways:

  • #1 RESTful Api Spec A web service may have an OpenAPI specification which describes all endpoints, parameters, responses, authentication schemes, etc. Such a specification is normally provided by developers.
  • #2 Manually input You can manually input the rules by adding a url, parameter name, max length and structure of the value.

The way #1 looks much better than #2. In a perfect world, each web service has an OpenAPI specification which is always available and up-to-date. But in the real world, it doesn’t seem to happen too often. A developer may change the APIs but forget to update the spec, or for some reason they don’t make the spec publicly available. In most cases, publicly available REST API have human-readable docs which is nice but it’s usually hard to use in an automated way.

  • But, APIGIT could make this easier.

APIGIT is a collaboration platform that stands out for its native Git support, which simplifies the API development process and version control, enabling users to easily design, document, mock, test, and share APIs. The platform's visual OpenAPI editor, in combination with its native Git support, makes it easy for team to collaborate and share their work in a seamless and efficient manner.

How does a RESTful Api Spec look like?

Here is part of a RESTful Api Spec.

"components": {
    "schemas": {
      "OpenAI-Request": {
        "type": "object",
        "properties": {
          "prompt": {
            "type": "string",
            "description": "Your question"
          "model": {
            "type": "string",
            "description": "OpenAI model",
            "default": "1",
            "minLength": 1,
            "maxLength": 20,
            "pattern": "\\w+"

When defining a schema in your RESTful API Spec, you have the ability to specify various aspects of a parameter, including its type, minimum and maximum length, and even a Regular Expression pattern. This specification can then be loaded into a Web Application Firewall (WAF), allowing you to generate customized rules that correspond to the defined schema.