Data Exposure in Strapi

Data exposure in Strapi APIs typically occurs through overly permissive role-based access control (RBAC) configurations, incorrect field-level permissions, and unintended exposure of sensitive data through API endpoints. The most common manifestation is when Strapi's default public content delivery endpoints are left enabled, allowing unauthenticated users to access data they shouldn't see.

In Strapi v4, the public API routes (e.g., /api/articles) are enabled by default for content types marked as 'Public'. This means that if you create a content type like 'User', 'Order', or 'Customer' and forget to disable public access, anyone can query your entire dataset. The issue compounds when these endpoints return more fields than intended, including sensitive information like email addresses, phone numbers, or internal IDs.

Another Strapi-specific pattern involves the find and findOne operations. Developers often configure permissions at the role level but forget to restrict individual fields. For example, a 'Customer' content type might have a 'billingAddress' field containing credit card information, but if field-level permissions aren't explicitly configured, this data becomes exposed through the API.

Strapi's dynamic zones and component system can also create data exposure scenarios. When components are reused across content types, a field that's properly secured in one context might be inadvertently exposed in another. Additionally, Strapi's media library integration can lead to exposure of private files if the 'public' flag is set incorrectly on uploaded assets.

The authentication system in Strapi can also contribute to data exposure. When using JWT tokens, improper token validation or overly broad permissions for authenticated users can allow them to access data from other users' accounts. This is particularly problematic in multi-tenant applications where users should only see their own data.

// Example of exposed endpoint in Strapi v4
// GET /api/users returns all user data
// GET /api/users/123 returns specific user data
// Both endpoints are public by default for 'Public' content types

Strapi's plugin system can also introduce data exposure. The 'content-type-builder' plugin, for instance, might expose API endpoints that should only be accessible to administrators. Similarly, the 'users-permissions' plugin's default configurations might grant broader access than intended.

Detecting data exposure in Strapi requires examining both the API surface and the permission configurations. Start by inventorying all content types and their API endpoints. For each content type, check whether it's marked as 'Public' and whether this aligns with your security requirements.

Use Strapi's admin panel to navigate to 'Content-Types Builder' and review each content type's permissions. Look for content types that have 'Public' access enabled but shouldn't. Pay special attention to content types with names suggesting sensitive data: 'User', 'Customer', 'Order', 'Payment', 'Profile', etc.

Field-level permissions are equally important. For each role (Public, Authenticated, Administrator), verify which fields are accessible. Strapi's permission interface shows a grid where you can see which roles can read or write each field. Any field containing sensitive information should be restricted appropriately.

API endpoint scanning is critical for detection. Tools like middleBrick can automatically scan your Strapi API endpoints and identify data exposure issues. middleBrick tests the unauthenticated attack surface by sending requests to all available endpoints and analyzing the responses for sensitive data patterns.

# Using middleBrick CLI to scan Strapi API
middlebrick scan https://your-strapi-api.com
# Returns security score with findings
# Identifies exposed endpoints and sensitive data

middleBrick's data exposure checks specifically look for patterns like email addresses, phone numbers, credit card numbers, SSNs, and other PII in API responses. It also verifies whether authentication is properly required for endpoints that should be protected.

Another detection method is examining Strapi's api/ directory structure. Each content type has an API controller that defines the available operations. Review these controllers to ensure they don't expose methods that should be restricted. Look for custom endpoints that might bypass the standard permission system.

Log analysis is also valuable. Check your Strapi logs for unexpected API calls or access patterns that might indicate data exposure. Look for requests to endpoints that should be protected or for unusual query patterns that suggest data scraping.

Remediating data exposure in Strapi involves configuring permissions correctly and implementing field-level security. The first step is to disable public access for any content type that shouldn't be publicly accessible. In Strapi's admin panel, navigate to 'Roles & Permissions' and ensure that only the appropriate roles have access to each content type.

For content types that must remain public (like blog posts or product listings), implement field-level restrictions to exclude sensitive data. Strapi allows you to control which fields are returned for each operation (find, findOne, create, update, delete). Use this to ensure that only necessary fields are exposed.

// Strapi v4 - Configuring field permissions in api.js
module.exports = ({ strapi }) => {
  return {
    async find(ctx) {
      // Only return non-sensitive fields
      const { results, pagination } = await strapi
        .query('user')
        .find(
          { 
            select: ['id', 'username', 'createdAt'] // exclude sensitive fields
          },
          [
            {
              role: ctx.state.user?.role?.id,
              user: ctx.state.user?.id,
            },
          ]
        );

      return {
        results,
        pagination,
      };
    },
  };
};

For sensitive content types, create custom controllers that enforce strict access controls. Override the default CRUD operations to implement additional validation and filtering. For example, ensure that users can only access their own data by filtering queries based on the authenticated user's ID.

javascript // Custom controller with data isolation module.exports = { async find(ctx) { const userId = ctx.state.user.id; // Only return records belonging to the authenticated user const entities = await strapi .query('order') .find({ user: userId, // filter by user ID select: ['id', 'amount', 'status', 'createdAt'] }); return entities; }, };

Implement API key authentication for endpoints that need to be accessible but require some form of identification. Strapi's plugin system supports API key authentication, which can be used to track and control access to sensitive endpoints without requiring full user authentication.

Use Strapi's lifecycle hooks to sanitize data before it's returned in API responses. The beforeFind and beforeFindOne hooks can be used to modify queries and ensure that sensitive data is never exposed, even if permissions are misconfigured.

// Lifecycle hook to prevent data exposure
module.exports = {
  lifecycles: {
    async beforeFind(params, populate) {
      // Remove sensitive fields from query results
      if (params.select) {
        params.select = params.select.filter(
          field => !['password', 'ssn', 'creditCard'].includes(field)
        );
      }
    },
  },
};

Regular security audits are essential for maintaining data exposure prevention. Use middleBrick's continuous monitoring capabilities to periodically scan your Strapi API and alert you to any new data exposure issues that might arise from configuration changes or code updates.