=== What is a Cross-site request forgery?

Cross-site request forgery, also known as one-click attack or session riding and abbreviated as CSRF
(sometimes pronounced sea-surf) or XSRF, is a type of malicious exploit of a website where unauthorized commands are transmitted
from a user that the website trusts. Unlike cross-site scripting (XSS), which exploits the trust a user has for a particular site, CSRF
exploits the trust that a site has in a user's browser.

A cross-site request forgery is a 'confused deputy' attack against a web browser. CSRF commonly has the following characteristics:

* It involves sites that rely on a user's identity.
* It exploits the site's trust in that identity.
* It tricks the user's browser into sending HTTP requests to a target site.
* It involves HTTP requests that have side effects.

At risk are web applications that perform actions based on input from trusted and authenticated users without requiring the user to authorize
the specific action. A user who is authenticated by a cookie saved in the user's web browser could unknowingly send an HTTP request to a site
that trusts the user and thereby causes an unwanted action.

A CSRF attack targets/abuses basic web functionality. If the site allows that causes a state change on the server, such as changing the victim's email address or password, or purchasing
something. Forcing the victim to retrieve data doesn't benefit an attacker because the attacker doesn't receive the response, the victim does.
As such, CSRF attacks target state-changing requests.

Let's continue with some exercises to address way to perform a CSRF request.
