Portswigger Academy CORS Labs

Introduction

What?

Cross-origin resource sharing (CORS) is a browser mechanism which enables controlled access to resources located outside of a given domain. It extends and adds flexibility to the same-origin policy (SOP).

Why?

It also provides potential for cross-domain attacks, if a website’s CORS policy is poorly configured and implemented.

How?

• Same-origin policy (SOP) vulnerabilities

• CORS vulnerability with basic origin reflection

• CORS vulnerability with trusted null origin

• CORS vulnerability with trusted insecure protocols

• CORS vulnerability with internal network pivot attack