CSRF stands for Cross-Site Request Forgery, which is a type of attack where a malicious actor tricks a user into performing unwanted actions on a web application in which the user is authenticated. The attacker essentially "forges" a request from the user's browser without their consent, taking advantage of the user's active session with the target website.

How CSRF Works:
1. User Authentication: The user logs into a website (e.g., a banking website) and receives a session cookie that keeps them authenticated.
2. User Visits a Malicious Site: While logged in, the user visits a malicious site or clicks on a malicious link.
3. Forged Request: The malicious site generates a hidden request (such as a form submission) to the target site (e.g., bank) on behalf of the user, utilizing the user's active session and browser cookies.
4. Unintended Action: Since the user is authenticated, the target site processes the request as valid, allowing the attacker to perform actions like transferring money, changing account details, etc.

CSRF Prevention Mechanisms:
To protect against CSRF, developers can implement several mechanisms:
1. CSRF Tokens: The most common and effective defense.
◦ Every form submission or sensitive request includes a hidden, random token (CSRF token) that is unique to the user's session.
◦ The server validates the token before processing the request, ensuring the request originated from a legitimate source.
2. SameSite Cookies: A modern defense where cookies are only sent with requests originating from the same site.
◦ Setting SameSite attribute in cookies can prevent browsers from sending cookies in cross-origin requests.
◦ Set-Cookie: sessionID=abc123; SameSite=Strict;
NextAuth.js and CSRF Protection:
In the context of NextAuth.js, CSRF protection is enabled by default when handling authentication requests. It ensures that malicious websites can’t perform unwanted actions on behalf of a logged-in user.
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