Click here to Skip to main content
13,343,328 members (54,328 online)
Click here to Skip to main content
Add your own
alternative version


146 bookmarked
Posted 29 Apr 2003

Windows Impersonation using C#

, 29 Apr 2003
Rate this:
Please Sign up or sign in to vote.
An article demonstrating how to use Windows impersonation in your C# code



I've been a member of the CodeProject for over 3 years now, and still haven't contributed any articles - until now.

While designing a Windows Forms-based application, to administrate containers in our Active Directory, I needed a way to allow binding to the AD using alternate credentials. Windows impersonation was the answer. This sample app demonstrates how to use unmanaged code by calling LogonUser() contained within the advapi32.dll, and pass a token handle back to your .NET application using WindowsImpersonationContext.

One of the downfalls to the LogonUser()function is that the password get passed in clear-text.

Partial Source Code

using System.Runtime.InteropServices; // DllImport
using System.Security.Principal; // WindowsImpersonationContext
using System.Security.Permissions; // PermissionSetAttribute

public WindowsImpersonationContext 
    ImpersonateUser(string sUsername, string sDomain, string sPassword)
    // initialize tokens
    IntPtr pExistingTokenHandle = new IntPtr(0);
    IntPtr pDuplicateTokenHandle = new IntPtr(0);
    pExistingTokenHandle = IntPtr.Zero;
    pDuplicateTokenHandle = IntPtr.Zero;
    // if domain name was blank, assume local machine
    if (sDomain == "")
        sDomain = System.Environment.MachineName;

        string sResult = null;

        const int LOGON32_PROVIDER_DEFAULT = 0;

        // create token
        const int LOGON32_LOGON_INTERACTIVE = 2;
        //const int SecurityImpersonation = 2;

        // get handle to token
        bool bImpersonated = LogonUser(sUsername, sDomain, sPassword, 
                ref pExistingTokenHandle);

        // did impersonation fail?
        if (false == bImpersonated)
            int nErrorCode = Marshal.GetLastWin32Error();
            sResult = "LogonUser() failed with error code: " + 
                nErrorCode + "\r\n";

            // show the reason why LogonUser failed
            MessageBox.Show(this, sResult, "Error", 
                MessageBoxButtons.OK, MessageBoxIcon.Error);

        // Get identity before impersonation
        sResult += "Before impersonation: " + 
            WindowsIdentity.GetCurrent().Name + "\r\n";

        bool bRetVal = DuplicateToken(pExistingTokenHandle, 
                ref pDuplicateTokenHandle);

        // did DuplicateToken fail?
        if (false == bRetVal)
            int nErrorCode = Marshal.GetLastWin32Error();
            // close existing handle
            sResult += "DuplicateToken() failed with error code: " 
                + nErrorCode + "\r\n";

            // show the reason why DuplicateToken failed
            MessageBox.Show(this, sResult, "Error", 
                MessageBoxButtons.OK, MessageBoxIcon.Error);
            return null;
            // create new identity using new primary token
            WindowsIdentity newId = new WindowsIdentity
            WindowsImpersonationContext impersonatedUser = 

            // check the identity after impersonation
            sResult += "After impersonation: " + 
                WindowsIdentity.GetCurrent().Name + "\r\n";
            MessageBox.Show(this, sResult, "Success", 
                MessageBoxButtons.OK, MessageBoxIcon.Information);
            return impersonatedUser;
    catch (Exception ex)
        throw ex;
        // close handle(s)
        if (pExistingTokenHandle != IntPtr.Zero)
        if (pDuplicateTokenHandle != IntPtr.Zero) 

Points of Interest

This code won't work on Windows 98 or ME because they do not utilize user tokens. Code was built and run using Visual Studio.NET 2002 on Windows XP Service Pack 1.

One of the other uses for this code I've found is, for instantiating COM components that must run in an alternate security context to that of the logged-on user.

If anyone has a more secure method of achieving the same thing, please let me know.


  • Version 1.0 - 04.25.03 - First release version


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Marc Merritt
United States United States
I live in beautiful Arizona, USA.

You may also be interested in...


Comments and Discussions

GeneralCreate a folder on a remote computer Pin
Shlomo6-Jan-10 2:52
memberShlomo6-Jan-10 2:52 
GeneralWindows 2008 server Pin
smithafebinkal3-Dec-08 19:45
membersmithafebinkal3-Dec-08 19:45 
GeneralRe: Windows 2008 server Pin
omar_chavez1-Dec-15 16:08
memberomar_chavez1-Dec-15 16:08 
GeneralThis process not working with a WPF application!!! Pin
Arshad Kunnath31-Jul-08 2:36
memberArshad Kunnath31-Jul-08 2:36 
GeneralRe: This process not working with a WPF application!!! Pin
Marc Merritt31-Jul-08 3:59
memberMarc Merritt31-Jul-08 3:59 
GeneralRe: This process not working with a WPF application!!! Pin
Matei Focseneanu12-May-10 6:15
memberMatei Focseneanu12-May-10 6:15 
GeneralRe: This process not working with a WPF application!!! Pin
Jason Jakob20-Jun-13 6:09
memberJason Jakob20-Jun-13 6:09 
QuestionIt may be.... Pin
Willian.BR15-May-08 9:55
memberWillian.BR15-May-08 9:55 
It's a nice work. Congratulations!


I would like to run a small windows service application.
It will make some tasks and than the service may run another
process but with other local credentials.
The main service will run under SYSTEM account.

Can you help me?


Willian S. Rodrigues

GeneralWindows CE .net Pin
questions_c1-Oct-07 3:28
memberquestions_c1-Oct-07 3:28 
GeneralRe: Windows CE .net Pin
Marc Merritt1-Oct-07 16:18
memberMarc Merritt1-Oct-07 16:18 
GeneralRe: Windows CE .net Pin
Pram_Singh4120-Jul-09 5:22
memberPram_Singh4120-Jul-09 5:22 
GeneralError Code 1326 [modified] Pin
collapo21-Aug-07 1:56
membercollapo21-Aug-07 1:56 
GeneralRe: Error Code 1326 Pin
mirh10-Oct-07 2:59
membermirh10-Oct-07 2:59 
GeneralRe: Error Code 1326 Pin
mustiy10-Feb-10 0:17
membermustiy10-Feb-10 0:17 
GeneralError 1314 Pin
m.aldegheri3-Aug-06 7:28
memberm.aldegheri3-Aug-06 7:28 
GeneralRe: Error 1314 Pin
m.aldegheri3-Aug-06 23:23
memberm.aldegheri3-Aug-06 23:23 
GeneralRe: Error 1314 Pin
MunkieFish11-Apr-07 8:49
memberMunkieFish11-Apr-07 8:49 
AnswerRe: Error 1314 Pin
uppals12-Apr-07 14:06
memberuppals12-Apr-07 14:06 
GeneralHelp needed Windows 2000 SP4 still getting 1314! -- Re: Error 1314 Pin
devvvy21-Feb-08 21:41
memberdevvvy21-Feb-08 21:41 
GeneralRe: Help needed Windows 2000 SP4 still getting 1314! -- Re: Error 1314 Pin
Marc Merritt26-Feb-08 4:02
memberMarc Merritt26-Feb-08 4:02 
Questionhow to use this in case of a local account? Pin
yossof elnaggar27-Jun-06 21:29
memberyossof elnaggar27-Jun-06 21:29 
AnswerRe: how to use this in case of a local account? Pin
hk1112-Jul-07 20:04
memberhk1112-Jul-07 20:04 
GeneralRe: how to use this in case of a local account? Pin
appalanaidu Aug20118-Feb-12 21:54
memberappalanaidu Aug20118-Feb-12 21:54 
GeneralFirst call takes too long Pin
schweeneh4-Apr-06 7:04
memberschweeneh4-Apr-06 7:04 
GeneralRe: First call takes too long Pin
Marc Merritt12-Jun-06 3:24
memberMarc Merritt12-Jun-06 3:24 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

Permalink | Advertise | Privacy | Terms of Use | Mobile
Web04 | 2.8.180111.1 | Last Updated 30 Apr 2003
Article Copyright 2003 by Marc Merritt
Everything else Copyright © CodeProject, 1999-2018
Layout: fixed | fluid