Impersonation and DirectoryEntry

Question

I am impersonating a user account successfully, but I am not able to use the impersonated account to bind to AD and pull down a DirectoryEntry.

The below code outputs:

• Before impersonation I am: DOMAIN\user
• After impersonation I am: DOMAIN\admin
• Error: C:\Users\user\ADSI_Impersonation\bin\Debug\ADSI_Impersonation.exe samaccountname:

My issue seems similar to:

How to use the System.DirectoryServices namespace in ASP.NET

I am obtaining a primary token. I understand that I need to use delegation to use the impersonated token on a remote computer. I confirmed that the account doesn't have the flag checked "Account is sensitive and cannot be delegated". I also confirmed that the Local Group Policy and Domain Group Policies are not preventing delegation:

Computer Configuration\Windows Settings\Security Settings\Local Policies\User Rights Assignment\

What am I missing?

Thanks!

using System;
using System.DirectoryServices;
using System.Security;
using System.Security.Principal;
using System.Runtime.InteropServices;
using Microsoft.Win32.SafeHandles;
using System.Runtime.ConstrainedExecution;

namespace ADSI_Impersonation
{
    class Program
    {
        [DllImport("advapi32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        public static extern bool LogonUser(String lpszUsername, String lpszDomain, String lpszPassword,
            int dwLogonType, int dwLogonProvider, out SafeTokenHandle phToken);

        [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
        public static extern bool CloseHandle(IntPtr handle);

        static void Main(string[] args)
        {
            const int LOGON32_PROVIDER_DEFAULT = 0;
            const int LOGON32_LOGON_INTERACTIVE = 2;

            string userName = "[email protected]";
            string password = "password";

            Console.WriteLine("Before impersonation I am: " + WindowsIdentity.GetCurrent().Name);

            SafeTokenHandle safeTokenHandle;

            try
            {
                bool returnValue = LogonUser(userName, null, password,
                    LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT,
                    out safeTokenHandle);

                if (returnValue)
                {
                    WindowsIdentity newId = new WindowsIdentity(safeTokenHandle.DangerousGetHandle());
                    WindowsImpersonationContext impersonatedUser = newId.Impersonate();
                }
                else
                {
                    Console.WriteLine("Unable to create impersonatedUser.");
                    return;
                }
            }
            catch (Exception e)
            {
                Console.WriteLine("Authentication error.\r\n" + e.Message);
            }

            Console.WriteLine("After impersonation I am: " + WindowsIdentity.GetCurrent().Name);

            string OU = "LDAP://dc=domain,dc=com";
            DirectoryEntry entry = new DirectoryEntry(OU);
            entry.AuthenticationType = AuthenticationTypes.Secure;

            DirectorySearcher mySearcher = new DirectorySearcher();
            mySearcher.SearchRoot = entry;
            mySearcher.SearchScope = System.DirectoryServices.SearchScope.Subtree;
            mySearcher.PropertiesToLoad.Add("cn");
            mySearcher.PropertiesToLoad.Add("samaccountname");

            string cn = "fistname mi. lastname";
            string samaccountname = "";

            try
            {
                // Create the LDAP query and send the request
                mySearcher.Filter = "(cn=" + cn + ")";

                SearchResultCollection searchresultcollection = mySearcher.FindAll();

                DirectoryEntry ADentry = searchresultcollection[0].GetDirectoryEntry();

                Console.WriteLine("samaccountname: " + ADentry.Properties["samaccountname"].Value.ToString());
            }
            catch (Exception e)
            {
                Console.WriteLine("Error: " + e.Message);
            }

            Console.WriteLine("samaccountname: " + samaccountname);
            Console.ReadLine();
        }
    }

    public sealed class SafeTokenHandle : SafeHandleZeroOrMinusOneIsInvalid
    {
        private SafeTokenHandle()
            : base(true)
        {
        }

        [DllImport("kernel32.dll")]
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
        [SuppressUnmanagedCodeSecurity]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool CloseHandle(IntPtr handle);

        protected override bool ReleaseHandle()
        {
            return CloseHandle(handle);
        }
    }
}

Answer 1

Many .NET APIs do not take your manual impersonation into consideration, such as the LDAP queries you noticed. Therefore, you need to use the overloading constructors of DirectoryEntry instead,

http://msdn.microsoft.com/en-us/library/bw8k1as4.aspx

http://msdn.microsoft.com/en-us/library/wh2h7eed.aspx