C# How to change user context in app running on system

Question

I have an application that runs with the system user. I need that some code in the app runs on user context (with the user itself). For example i need to use the webclient in user context because that way my firewall recognize the username, but later i need to run some other code ex. Running a exe in system context (with system user) because i need the privileges.

Is there a way to do this?.

Thanks!!!

Answer 1

I have used this code to impersonate certain operations

using System;
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Security.Principal;
using NLog;
namespace Core.Impersonation
{
    public class ImpersonatedUser : IDisposable
    {
        private static Logger logger = LogManager.GetCurrentClassLogger();
        IntPtr userHandle;
        WindowsImpersonationContext impersonationContext;
        public ImpersonatedUser(string user, string domain, string password)
        {
            logger.Debug("Impersonating user: " + domain + @"\" + user);
            userHandle = IntPtr.Zero;
            bool loggedOn = LogonUser(
                user,
                domain,
                password,
                LogonType.Interactive,
                LogonProvider.Default,
                out userHandle);

            if (!loggedOn)
                throw new Win32Exception(Marshal.GetLastWin32Error());

            // Begin impersonating the user
            impersonationContext = WindowsIdentity.Impersonate(userHandle);
        }

        public void Dispose()
        {
            if (userHandle != IntPtr.Zero)
            {
                CloseHandle(userHandle);
                userHandle = IntPtr.Zero;
                impersonationContext.Undo();
                logger.Debug("Finished Impersonating user");
            }
        }

        [DllImport("advapi32.dll", SetLastError = true)]
        static extern bool LogonUser(
            string lpszUsername,
            string lpszDomain,
            string lpszPassword,
            LogonType dwLogonType,
            LogonProvider dwLogonProvider,
            out IntPtr phToken
            );

        [DllImport("kernel32.dll", SetLastError = true)]
        static extern bool CloseHandle(IntPtr hHandle);

        enum LogonType : int
        {
            Interactive = 2,
            Network = 3,
            Batch = 4,
            Service = 5,
            NetworkCleartext = 8,
            NewCredentials = 9,
        }

        enum LogonProvider : int
        {
            Default = 0,
        }
    }
}

and then usage:

using (var i = new ImpersonatedUser("someLogin", "someDomain", "thePassword"))
{
    var u = System.Environment.UserName;
}