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description: Explains what Cross-Site Request Forgery (CSRF) is using a banking transfer example, then introduces ASP.NET MVC's built-in protections: the...
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# Help, I've inherited an ASP.NET MVC Core code base with no Cross-Site Request Forgery (CSRF) measures!

**[Maarten Balliauw](https://daily.dev/sources/maartenballiauw)** · 6 min read · 0 upvotes · 0 comments

## Summary

Explains what Cross-Site Request Forgery (CSRF) is using a banking transfer example, then introduces ASP.NET MVC's built-in protections: the @Html.AntiForgeryToken() helper, the [ValidateAntiForgeryToken] attribute, and the newer [AutoValidateAntiforgeryTokenAttribute] global filter. Sets up a series on finding action methods in an inherited codebase that lack these CSRF protections, with follow-up posts covering structural search and replace, plus unit testing approaches.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://blog.maartenballiauw.be/posts/2019-01-09-help-ive-inherited-an-aspnet-mvc-core-code-base-with-no-cross-site-request-forgery-csrf-measures>

## Questions this post answers

### How do I prevent CSRF attacks in ASP.NET Core MVC?

Use the @Html.AntiForgeryToken() helper to add a hidden field token to forms, and decorate POST/PUT/PATCH/DELETE action methods with the [ValidateAntiForgeryToken] attribute. The framework automatically sets a session token cookie, and validation fails with an exception if the field token and session token don't match, blocking forged cross-site requests.

_daily.dev surfaces practical security write-ups for developers hardening legacy ASP.NET codebases against CSRF._

### What is an alternative to adding [ValidateAntiForgeryToken] on every action method in ASP.NET Core?

Apply the [AutoValidateAntiforgeryTokenAttribute] as a global filter, which automatically triggers anti-forgery token validation by default for all HTTP methods except GET, HEAD, OPTIONS, and TRACE. For exceptional cases where CSRF validation isn't needed, use the [IgnoreAntiforgeryTokenAttribute] to opt out on specific actions.

_Developers weighing explicit versus global CSRF protection strategies can find more framework deep-dives on daily.dev._

## Similar posts on daily.dev

- [CSRF from Scratch: Browser Mechanics, Attacks, and Spring Security Implementation \[Full Handbook\]](https://daily.dev/posts/csrf-from-scratch-browser-mechanics-attacks-and-spring-security-implementation-full-handbook--4km8mrcii) · freeCodeCamp · 17 upvotes · 4 comments
- [CSRF Attack Explained: Mechanics, Real Exploits, and How to Test for It](https://daily.dev/posts/csrf-attack-explained-mechanics-real-exploits-and-how-to-test-for-it-lkzyruhyf) · Latest Hacking News · 0 upvotes · 0 comments
- [CSRF Protection without Tokens or Hidden Form Fields](https://daily.dev/posts/csrf-protection-without-tokens-or-hidden-form-fields-a651bvhew) · Hacker News · 0 upvotes · 0 comments
- [ASP.NET Core Security Explained: Modern Authentication, Authorization, and JWT](https://daily.dev/posts/asp-net-core-security-explained-modern-authentication-authorization-and-jwt-bgq4u3gn4) · Syncfusion · 4 upvotes · 0 comments

---

Tags: [#security](https://daily.dev/tags/security), [#c#](https://daily.dev/tags/c#), [#aspnet](https://daily.dev/tags/aspnet), [#web-security](https://daily.dev/tags/web-security)

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