.. _install_sandboxes_csrf: CSRF filter =========== .. sidebar:: Requirements .. include:: _include/docker-env-setup-link.rst Cross-Site Request Forgery (CSRF) is an attack that occurs when a malicious third-party website exploits a vulnerability that allows them to submit an undesired request on a user's behalf. To mitigate this attack this filter checks where a request is coming from to determine if the request's origin is the same as it's destination. To help demonstrate how front-envoy can enforce CSRF policies, we are releasing a `docker compose `_ sandbox that deploys a service with both a frontend and backed. This service will be started on two different virtual machines with different origins. The frontend has a field to input the remote domain of where you would like to send POST requests along with radio buttons to select the remote domain's CSRF enforcement. The CSRF enforcement choices are: * Disabled: CSRF is disabled on the requested route. This will result in a successful request since there is no CSRF enforcement. * Shadow Mode: CSRF is not enforced on the requested route but will record if the request contains a valid source origin. * Enabled: CSRF is enabled and will return a 403 (Forbidden) status code when a request is made from a different origin. * Ignored: CSRF is enabled but the request type is a GET. This should bypass the CSRF filter and return successfully. Step 1: Start all of our containers *********************************** Change to the ``examples/csrf/samesite`` directory, and start the containers: .. code-block:: console $ pwd envoy/examples/csrf/samesite $ docker-compose pull $ docker-compose up --build -d $ docker-compose ps Name Command State Ports ---------------------------------------------------------------------------------------------------------------------------- samesite_front-envoy_1 /docker-entrypoint.sh /bin ... Up 10000/tcp, 0.0.0.0:8000->8000/tcp, 0.0.0.0:8001->8001/tcp samesite_service_1 /bin/sh -c /usr/local/bin/ ... Up 10000/tcp, 8000/tcp Now, switch to the ``crosssite`` directory in the ``csrf`` example, and start the containers: .. code-block:: console $ pwd envoy/examples/csrf/crosssite $ docker-compose up --build -d $ docker-compose ps Name Command State Ports ----------------------------------------------------------------------------------------------------- crosssite_front-envoy_1 /bin/sh -c /usr/local/bin/ ... Up 10000/tcp, 0.0.0.0:8002->8000/tcp crosssite_service_1 /docker-entrypoint.sh /bin ... Up 10000/tcp Step 2: Test Envoy's CSRF capabilities ************************************** You can now open a browser at http://localhost:8002 to view your ``crosssite`` frontend service. Enter the IP of the ``samesite`` machine to demonstrate cross-site requests. Requests with the enabled enforcement will fail. By default this field will be populated with ``localhost``. To demonstrate same-site requests open the frontend service for ``samesite`` at http://localhost:8000 and enter the IP address of the ``samesite`` machine as the destination. Results of the cross-site request will be shown on the page under *Request Results*. Your browser's ``CSRF`` enforcement logs can be found in the browser console and in the network tab. For example: .. code-block:: console Failed to load resource: the server responded with a status of 403 (Forbidden) If you change the destination to be the same as one displaying the website and set the ``CSRF`` enforcement to enabled the request will go through successfully. Step 3: Check stats of backend via admin **************************************** When Envoy runs, it can listen to ``admin`` requests if a port is configured. In the example configs, the backend admin is bound to port ``8001``. If you browse to http://localhost:8001/stats you will be able to view all of the Envoy stats for the backend. You should see the CORS stats for invalid and valid origins increment as you make requests from the frontend cluster. .. code-block:: none http.ingress_http.csrf.missing_source_origin: 0 http.ingress_http.csrf.request_invalid: 1 http.ingress_http.csrf.request_valid: 0 .. seealso:: :ref:`Envoy admin quick start guide ` Quick start guide to the Envoy admin interface.