Skip to main content

Impersonation in ASP.NET Core

A colleague reached out to me with a specific scenario he had to tackle. He had an IIS hosted ASP.NET Core application using Windows Authentication where he had to execute a specific action on behalf of the current user. The typical way to do this is through impersonation. In this post I’ll explain what impersonation is and how you can get this working in ASP.NET Core.

What is impersonation?

Impersonation is a security feature that allows an application to execute code under the context of a different user identity. This capability is often used when an application needs to access resources, such as files, databases, or network services, with permissions different from those of the current user or the application's process.

By using impersonation the application temporarily assumes the identity of another user to perform specific actions, reverting back to its original identity afterward.

Some common use cases for impersonation are:

  • Accessing network shares or file systems with restricted permissions.

  • Performing administrative tasks that require elevated privileges.

  • Connecting to databases using Windows Authentication.

Impersonation in ASP.NET Core

In classic ASP.NET, impersonation could be enabled through the web.config file. However, ASP.NET Core does not support this configuration-based impersonation. Instead, impersonation must be handled programmatically using the use WindowsIdentity.RunImpersonated or RunImpersonatedAsync.

Here’s a basic example demonstrating how to implement impersonation in an ASP.NET Core application:

Remark: In the example above we are using middleware to run our impersonated code but you can also use an action filter if you want(Let me know if I should add an example).

Make sure that when trying the code above that you have the following configuration set in IIS:

  • Enable Windows Authentication in IIS Manager.

  • Disable Anonymous Authentication if not required.

  • Ensure the application pool identity has the necessary permissions for delegation if needed.

More information

Configure Windows Authentication in ASP.NET Core | Microsoft Learn

Labels:

Popular posts from this blog

.NET 8–Keyed/Named Services

A feature that a lot of IoC container libraries support but that was missing in the default DI container provided by Microsoft is the support for Keyed or Named Services. This feature allows you to register the same type multiple times using different names, allowing you to resolve a specific instance based on the circumstances. Although there is some controversy if supporting this feature is a good idea or not, it certainly can be handy. To support this feature a new interface IKeyedServiceProvider got introduced in .NET 8 providing 2 new methods on our ServiceProvider instance: object? GetKeyedService(Type serviceType, object? serviceKey); object GetRequiredKeyedService(Type serviceType, object? serviceKey); To use it, we need to register our service using one of the new extension methods: Resolving the service can be done either through the FromKeyedServices attribute: or by injecting the IKeyedServiceProvider interface and calling the GetRequiredKeyedServic...
Read more

Azure DevOps/ GitHub emoji

I’m really bad at remembering emoji’s. So here is cheat sheet with all emoji’s that can be used in tools that support the github emoji markdown markup: All credits go to rcaviers who created this list.
Read more

Kubernetes–Limit your environmental impact

Reducing the carbon footprint and CO2 emission of our (cloud) workloads, is a responsibility of all of us. If you are running a Kubernetes cluster, have a look at Kube-Green . kube-green is a simple Kubernetes operator that automatically shuts down (some of) your pods when you don't need them. A single pod produces about 11 Kg CO2eq per year( here the calculation). Reason enough to give it a try! Installing kube-green in your cluster The easiest way to install the operator in your cluster is through kubectl. We first need to install a cert-manager: kubectl apply -f https://github.com/cert-manager/cert-manager/releases/download/v1.14.5/cert-manager.yaml Remark: Wait a minute before you continue as it can take some time before the cert-manager is up & running inside your cluster. Now we can install the kube-green operator: kubectl apply -f https://github.com/kube-green/kube-green/releases/latest/download/kube-green.yaml Now in the namespace where we want t...
Read more