How to Impersonate local system account in c#

The following code snippet shows how to impersonate using C#.

You can easily impersonate by calling Impersonator.Impersonate("domain","username","password"); method.

public class Impersonator
    {
        [DllImport("advapi32.dll", SetLastError = true)]
        public static extern bool LogonUser(String lpszUsername, String lpszDomain, String lpszPassword,
            int dwLogonType, int dwLogonProvider, ref IntPtr phToken);

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

        [DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        public extern static bool DuplicateToken(IntPtr ExistingTokenHandle,
            int SECURITY_IMPERSONATION_LEVEL, ref IntPtr DuplicateTokenHandle);

        public static bool Impersonate(string domain, string userName, string password)
        {
            IntPtr tokenHandle = new IntPtr(0);
            IntPtr dupeTokenHandle = new IntPtr(0);
            bool returnValue
            try
            {
                const int LOGON32_PROVIDER_DEFAULT = 0;
                const int LOGON32_LOGON_INTERACTIVE = 2;

                tokenHandle = IntPtr.Zero;
                dupeTokenHandle = IntPtr.Zero;

                // Call LogonUser to obtain a handle to an access token.
                returnValue = LogonUser(userName, domain, password,
                    LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT,
                    ref tokenHandle);

            }
            catch (Exception ex)
            {
                returnValue=false;
                Console.WriteLine("Exception occurred. " + ex.Message);
            }
            return returnValue;
        }
    }

Above code may not be unsafe for exception handling. I made it shorter for your easier understanding. Please go to http://msdn.microsoft.com/en-us/library/system.security.principal.windowsidentity.impersonate(VS.71).aspx for more information.

2 Replies

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Rajesh Vellore17y ago
How can we do impersonation in windows service for NT AUTHORITY\\SYSTEM of local system. I am able to do the impersonation for normal users only for "System" i am not able to do.
zirano latt17y ago
The following code snippet shows how to impersonate using C#.

You can easily impersonate by calling Impersonator.Impersonate("domain","username","password"); method.

public class Impersonator
    {
        [DllImport("advapi32.dll", SetLastError = true)]
        public static extern bool LogonUser(String lpszUsername, String lpszDomain, String lpszPassword,
            int dwLogonType, int dwLogonProvider, ref IntPtr phToken);

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

        [DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        public extern static bool DuplicateToken(IntPtr ExistingTokenHandle,
            int SECURITY_IMPERSONATION_LEVEL, ref IntPtr DuplicateTokenHandle);

        public static bool Impersonate(string domain, string userName, string password)
        {
            IntPtr tokenHandle = new IntPtr(0);
            IntPtr dupeTokenHandle = new IntPtr(0);
            bool returnValue
            try
            {
                const int LOGON32_PROVIDER_DEFAULT = 0;
                const int LOGON32_LOGON_INTERACTIVE = 2;

                tokenHandle = IntPtr.Zero;
                dupeTokenHandle = IntPtr.Zero;

                // Call LogonUser to obtain a handle to an access token.
                returnValue = LogonUser(userName, domain, password,
                    LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT,
                    ref tokenHandle);

            }
            catch (Exception ex)
            {
                returnValue=false;
                Console.WriteLine("Exception occurred. " + ex.Message);
            }
            return returnValue;
        }
    }

Above code may not be unsafe for exception handling. I made it shorter for your easier understanding. Please go to http://msdn.microsoft.com/en-us/library/system.security.principal.windowsidentity.impersonate(VS.71).aspx for more information.