Overview

This skill empowers Claude to assess the security and correctness of CORS policies. By leveraging the cors-policy-validator plugin, it identifies misconfigurations and potential vulnerabilities in CORS settings, helping developers build more secure web applications.

How It Works

1. Analyze CORS Configuration: The skill receives the CORS configuration details, such as headers or policy files.
2. Validate Policy: It utilizes the cors-policy-validator plugin to analyze the provided configuration against established security best practices.
3. Report Findings: The skill presents a detailed report outlining any identified vulnerabilities or misconfigurations in the CORS policy.

When to Use This Skill

This skill activates when you need to:

• Validate a CORS policy for a web application.
• Check the CORS configuration of an API endpoint.
• Identify potential security vulnerabilities in existing CORS implementations.

Examples

Example 1: Validating a CORS Policy File

User request: "Validate the CORS policy in cors_policy.json"

The skill will:

1. Read the cors_policy.json file.
2. Use the cors-policy-validator plugin to analyze the CORS configuration.
3. Output a report detailing any identified vulnerabilities or misconfigurations.

Example 2: Checking CORS Headers for an API Endpoint

User request: "Check CORS headers for the API endpoint at https://example.com/api"

The skill will:

1. Fetch the CORS headers from the specified API endpoint.
2. Use the cors-policy-validator plugin to analyze the headers.
3. Output a report summarizing the CORS configuration and any potential issues.

Best Practices

• Configuration Source: Always specify the source of the CORS configuration (e.g., file path, URL) for accurate validation.
• Regular Validation: Regularly validate CORS policies, especially after making changes to the application or API.
• Heuristic Analysis: Consider supplementing validation with manual review and heuristic analysis to catch subtle vulnerabilities.

Integration

This skill can be integrated with other security-related plugins to provide a more comprehensive security assessment. For example, it can be used in conjunction with vulnerability scanning tools to identify potential cross-site scripting (XSS) vulnerabilities related to CORS misconfigurations.