1. 用户登录www.good-banking-site.example.com网站，服务器对用户进行身份验证并返回包含身份验证 Cookie 的响应。该站点容易受到攻击，因为它信任任何带有有效身份验证 Cookie 的请求。
2. 用户无访问了恶意站点：www.bad-crook-site.example.com.恶意站点包含了如下代码：
<h1>Congratulations! You're a Winner!</h1><form action="https://good-banking-site.com/api/account" method="post"><input type="hidden" name="Transaction" value="withdraw" /><input type="hidden" name="Amount" value="1000000" /><input type="submit" value="Click to collect your prize!" /></form>
注意这个恶意站点的action是指向安全站点的地址，用户点击Submit提交按钮。
CSRF 攻击之所以可能发生在使用 Cookie 进行身份验证的 Web 应用中，是因为：
using Microsoft.AspNetCore.Antiforgery;var builder = WebApplication.CreateBuilder();builder.Services.AddAntiforgery(options =>{options.Cookie.Name = "AntiForgery";options.Cookie.Domain = "localhost";options.Cookie.Path = "/";options.FormFieldName = "Antiforgery";options.Cookie.SecurePolicy = CookieSecurePolicy.SameAsRequest;});var app = builder.Build();//These are the four default services available at Configureapp.Run(async context =>{var antiForgery = context.RequestServices.GetService<IAntiforgery>();if (HttpMethods.IsPost(context.Request.Method)){await antiForgery.ValidateRequestAsync(context);await context.Response.WriteAsync("Response validated with anti forgery");return;}var token = antiForgery.GetAndStoreTokens(context);context.Response.Headers.Append("Content-Type", "text/html");await context.Response.WriteAsync($@"<html><body>View source to see the generated anti forgery token<form method=""post""><input type=""hidden"" name=""{token.FormFieldName}"" value=""{token.RequestToken}"" /><input type=""submit"" value=""Push""/></form></body></html>");});app.Run();
上面代码中:
[ValidateAntiForgeryToken] 特性，除了使用上面方法之外，还可以使用该特性在Action上进行验证。
