Can't login user to Azure AD using a bearer token without cookies

Question

Right now I'm hitting an API that uses Azure AD to authenticate users. Using a bearer token results in a HTTP 302 error redirecting users to login. However, if I have a few cookies, the GET request goes through fine.

How come the bearer token is not acceptable on it's own, and needs cookies? Is there a way around this?

Answer 1

If you are using .net core and you want to use an access token to auth requests, pls make sure that you are using AzureADBearer as your Authentication service.

Go to Startup.cs and try the code below :

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authentication.AzureAD.UI;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace WebApplicationAzureAD
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddAuthentication(AzureADDefaults.BearerAuthenticationScheme)
                .AddAzureADBearer(options => Configuration.Bind("AzureAd", options));
            services.AddControllers();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseHttpsRedirection();

            app.UseRouting();

            app.UseAuthentication();
            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }
}

Content of appsettings.json

{
  "AzureAd": {
    "Instance": "https://login.microsoftonline.com/",
    "Domain": "<your tenant domain>",
    "TenantId": "<your tenant ID>",
    "ClientId": "<your client ID>"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*"
}