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Database

Ruby Cors Wildcard Origin

Description

Detects insecure CORS (Cross-Origin Resource Sharing) configurations in Ruby on Rails applications that use wildcard (*) origins. Using wildcard CORS origins allows any external domain to make cross-origin requests to your application, potentially exposing sensitive data to malicious websites.

Weakness:

134 - Insecure or unset HTTP headers - CORS

Category: Protocol Manipulation

Detection Strategy

    • Identifies Rack::Cors middleware configurations in Ruby code

    • Examines CORS configuration settings to detect wildcard (*) origins

    • Reports a vulnerability when CORS is configured to allow requests from any origin (*)

    • Focuses on Rails middleware setup code where CORS rules are defined

Vulnerable code example

Rails.application.config.middleware.insert_before 0, Rack::Cors do
  allow do
    origins '*'  # ⚠️ Vulnerable: Allows requests from any origin
    resource '*',
             headers: :any,
             methods: [:get, :post, :options],
             credentials: true  # Critical: Allowing credentials with wildcard origin is dangerous
  end...

✅ Secure code example

Rails.application.config.middleware.insert_before 0, Rack::Cors do
  allow do
    origins 'https://trusted-frontend.example.com' # Only allow specific trusted domain
    resource '*',
             headers: :any, 
             methods: [:get, :post, :options],
             credentials: true,
             expose: ['Authorization'] # Explicitly specify exposed headers...