Identification of CORS Policy

Identifying insecure Cross-Origin Resource Sharing (CORS) policies involves examining how CORS is configured within web applications and ensuring that it is set up securely to mitigate the risks associated with cross-origin requests. Insecure CORS policies can lead to various security vulnerabilities, such as unauthorized data access, CSRF attacks, or information leakage. Here's how you can identify insecure CORS policies:


  1. Reviewing CORS Headers: Examine the CORS-related headers, such as Access-Control-Allow-Origin, Access-Control-Allow-Methods, Access-Control-Allow-Headers, and Access-Control-Allow-Credentials, in the HTTP responses from the server.
  2. Analyzing Access-Control-Allow-Origin: Verify the value of the Access-Control-Allow-Origin header to see if it allows requests from all origins (``) or from specific origins. Allowing requests from all origins may expose the application to security risks.
  3. Testing for Wildcard Usage: Check if the Access-Control-Allow-Origin header uses a wildcard (``) to allow requests from any origin. Wildcard usage is generally discouraged as it can open the application to attacks, such as CSRF.
  4. Analyzing Access-Control-Allow-Methods: Review the Access-Control-Allow-Methods header to ensure that only safe HTTP methods (e.g., GET, POST, HEAD) are allowed for cross-origin requests. Allowing unsafe methods (e.g., PUT, DELETE) can increase the attack surface.
  5. Inspecting Access-Control-Allow-Headers: Verify the Access-Control-Allow-Headers header to see if it allows additional headers beyond the default ones. Allowing overly permissive headers can expose sensitive information or facilitate attacks.
  6. Checking Access-Control-Allow-Credentials: Review the Access-Control-Allow-Credentials header to see if it allows credentials (cookies, HTTP authentication) to be sent with cross-origin requests. Allowing credentials without proper validation can lead to security risks.


  • Example 1: During testing, a penetration tester discovers that the application's CORS policy allows requests from any origin (Access-Control-Allow-Origin: *). This insecure configuration exposes the application to potential CSRF attacks.
  • Example 2: The tester finds that the application's CORS policy allows all HTTP methods (Access-Control-Allow-Methods: *). This overly permissive configuration increases the risk of unauthorized actions being performed by cross-origin requests.


  1. Restrict Origins: Configure the Access-Control-Allow-Origin header to allow requests only from trusted origins or domains instead of using a wildcard (``). Use specific origin values to reduce the attack surface.
  2. Limit Allowed Methods: Specify the allowed HTTP methods in the Access-Control-Allow-Methods header to restrict cross-origin requests to safe methods only. Avoid allowing unsafe methods unless necessary.
  3. Minimize Allowed Headers: Limit the allowed headers in the Access-Control-Allow-Headers header to only those required by the application. Avoid allowing overly permissive headers that could expose sensitive information.
  4. Use Credentials Sparingly: Set the Access-Control-Allow-Credentials header to true only if the application requires cross-origin requests with credentials. Ensure that proper validation and authentication mechanisms are in place.
  5. Regular Security Audits: Conduct regular security audits and vulnerability assessments to identify and address insecure CORS policies in web applications.
  6. Security Awareness Training: Educate developers about CORS security best practices and the risks associated with insecure CORS configurations in web applications.

By identifying and mitigating insecure CORS policies, organizations can reduce the risk of unauthorized access and protect the integrity and confidentiality of their web applications and data.