Process.Start() impersonation problem

Question

Trying to start process with another access token, without success, it runs as the non-impersonated user.

using (WindowsIdentity identity = new WindowsIdentity(token))
using (identity.Impersonate())
{
    Process.Start("blabla.txt");
}

How to make this work properly?

Scorbutic

Answer 1

You need to set the ProcessStartInfo.UserName and Password properties. With UseShellExecute set to false. If you only have a token then pinvoke CreateProcessAsUser().

Guanaco

When setting UseShellExecute to false, I can't start non-exe files like blabla.txt, so this option is not good for me. – Scorbutic

Well, getting the path to the .exe that is associated with the filename extension is an entirely different question. Well covered by other SO threads, no need to repeat it here. ShellExecuteEx() just doesn't support creating a process with a different (restricted) user token. That option is not good for you. – Guanaco

CreateProcessAsUser does not have Exited notifications, etc. I have legacy code that starts a process filling in ProcessStartInfo, subscribes to Exited and calls process.Start somewhere else. I'm trying to port this code so it can work with a given token and it looks that I'll have to write all the infrastructure myself... Quite a bit of work. Unless Keivan answer works. I need to try that first. – Santiagosantillan

Answer 2

Try this example from http://msdn.microsoft.com/en-us/library/w070t6ka.aspx

private static void ImpersonateIdentity(IntPtr logonToken)
{
    // Retrieve the Windows identity using the specified token.
    WindowsIdentity windowsIdentity = new WindowsIdentity(logonToken);

    // Create a WindowsImpersonationContext object by impersonating the
    // Windows identity.
    WindowsImpersonationContext impersonationContext =
        windowsIdentity.Impersonate();

    Console.WriteLine("Name of the identity after impersonation: "
        + WindowsIdentity.GetCurrent().Name + ".");

    //Start your process here
    Process.Start("blabla.txt");

    Console.WriteLine(windowsIdentity.ImpersonationLevel);
    // Stop impersonating the user.
    impersonationContext.Undo();

    // Check the identity name.
    Console.Write("Name of the identity after performing an Undo on the");
    Console.WriteLine(" impersonation: " +
        WindowsIdentity.GetCurrent().Name);
}

You can also use CreateProcessAsUser windows function.

http://www.pinvoke.net/default.aspx/advapi32/createprocessasuser.html

Fidelafidelas

CreateProcessAsUser can't start non-exe files like blabla.txt, so this option is not good for me. – Scorbutic

I know this is a bit old, but can't you just use the code Keivan posted and for the line to start the process use: Process.Start("notepad.exe blabla.txt"); – Prut

Answer 3

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Data.Common;
using System.Diagnostics;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.NetworkInformation;
using System.Net.Sockets;
using System.Runtime.InteropServices;
using System.Security;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Security.Principal;
using System.Security.Permissions;
using Microsoft.Win32.SafeHandles;
using System.Runtime.ConstrainedExecution;
using System.ComponentModel;

public static class ImpersonationUtils
{
    private const int SW_SHOW = 5;
    private const int TOKEN_QUERY = 0x0008;
    private const int TOKEN_DUPLICATE = 0x0002;
    private const int TOKEN_ASSIGN_PRIMARY = 0x0001;
    private const int STARTF_USESHOWWINDOW = 0x00000001;
    private const int STARTF_FORCEONFEEDBACK = 0x00000040;
    private const int CREATE_UNICODE_ENVIRONMENT = 0x00000400;
    private const int TOKEN_IMPERSONATE = 0x0004;
    private const int TOKEN_QUERY_SOURCE = 0x0010;
    private const int TOKEN_ADJUST_PRIVILEGES = 0x0020;
    private const int TOKEN_ADJUST_GROUPS = 0x0040;
    private const int TOKEN_ADJUST_DEFAULT = 0x0080;
    private const int TOKEN_ADJUST_SESSIONID = 0x0100;
    private const int STANDARD_RIGHTS_REQUIRED = 0x000F0000;
    private const int TOKEN_ALL_ACCESS =
        STANDARD_RIGHTS_REQUIRED |
        TOKEN_ASSIGN_PRIMARY |
        TOKEN_DUPLICATE |
        TOKEN_IMPERSONATE |
        TOKEN_QUERY |
        TOKEN_QUERY_SOURCE |
        TOKEN_ADJUST_PRIVILEGES |
        TOKEN_ADJUST_GROUPS |
        TOKEN_ADJUST_DEFAULT |
        TOKEN_ADJUST_SESSIONID;

    [StructLayout(LayoutKind.Sequential)]
    private struct PROCESS_INFORMATION
    {
        public IntPtr hProcess;
        public IntPtr hThread;
        public int dwProcessId;
        public int dwThreadId;
    }

    [StructLayout(LayoutKind.Sequential)]
    private struct SECURITY_ATTRIBUTES
    {
        public int nLength;
        public IntPtr lpSecurityDescriptor;
        public bool bInheritHandle;
    }

    [StructLayout(LayoutKind.Sequential)]
    private struct STARTUPINFO
    {
        public int cb;
        public string lpReserved;
        public string lpDesktop;
        public string lpTitle;
        public int dwX;
        public int dwY;
        public int dwXSize;
        public int dwYSize;
        public int dwXCountChars;
        public int dwYCountChars;
        public int dwFillAttribute;
        public int dwFlags;
        public short wShowWindow;
        public short cbReserved2;
        public IntPtr lpReserved2;
        public IntPtr hStdInput;
        public IntPtr hStdOutput;
        public IntPtr hStdError;
    }

    private enum SECURITY_IMPERSONATION_LEVEL
    {
        SecurityAnonymous,
        SecurityIdentification,
        SecurityImpersonation,
        SecurityDelegation
    }

    private enum TOKEN_TYPE
    {
        TokenPrimary = 1,
        TokenImpersonation
    }


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

    enum LogonProvider
    {
        LOGON32_PROVIDER_DEFAULT = 0,
        LOGON32_PROVIDER_WINNT35 = 1,
        LOGON32_PROVIDER_WINNT40 = 2,
        LOGON32_PROVIDER_WINNT50 = 3
    }

    [DllImport("advapi32.dll", SetLastError = true)]
    private static extern bool CreateProcessAsUser(
        IntPtr hToken,
        string lpApplicationName,
        string lpCommandLine,
        ref SECURITY_ATTRIBUTES lpProcessAttributes,
        ref SECURITY_ATTRIBUTES lpThreadAttributes,
        bool bInheritHandles,
        int dwCreationFlags,
        IntPtr lpEnvironment,
        string lpCurrentDirectory,
        ref STARTUPINFO lpStartupInfo,
        out PROCESS_INFORMATION lpProcessInformation);

    [DllImport("advapi32.dll", SetLastError = true)]
    private static extern bool DuplicateTokenEx(
        IntPtr hExistingToken,
        int dwDesiredAccess,
        ref SECURITY_ATTRIBUTES lpThreadAttributes,
        int ImpersonationLevel,
        int dwTokenType,
        ref IntPtr phNewToken);

    [DllImport("advapi32.dll", SetLastError = true)]
    private static extern bool OpenProcessToken(
        IntPtr ProcessHandle,
        int DesiredAccess,
        ref IntPtr TokenHandle);

    [DllImport("userenv.dll", SetLastError = true)]
    private static extern bool CreateEnvironmentBlock(
        ref IntPtr lpEnvironment,
        IntPtr hToken,
        bool bInherit);

    [DllImport("userenv.dll", SetLastError = true)]
    private static extern bool DestroyEnvironmentBlock(
        IntPtr lpEnvironment);

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

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

    public static void LaunchProcessAsUser(string cmdLine, IntPtr token, IntPtr envBlock, int sessionId)
    {
        var pi = new PROCESS_INFORMATION();
        var saProcess = new SECURITY_ATTRIBUTES();
        var saThread = new SECURITY_ATTRIBUTES();
        saProcess.nLength = Marshal.SizeOf(saProcess);
        saThread.nLength = Marshal.SizeOf(saThread);

        var si = new STARTUPINFO();
        si.cb = Marshal.SizeOf(si);
        si.lpDesktop = @"WinSta0\Default";
        si.dwFlags = STARTF_USESHOWWINDOW | STARTF_FORCEONFEEDBACK;
        si.wShowWindow = SW_SHOW;

        if (!CreateProcessAsUser(
            token,
            null,
            cmdLine,
            ref saProcess,
            ref saThread,
            false,
            CREATE_UNICODE_ENVIRONMENT,
            envBlock,
            null,
            ref si,
            out pi))
        {
            throw new Win32Exception(Marshal.GetLastWin32Error(), "CreateProcessAsUser En Echec");
        }
    }

    private static IDisposable Impersonate(IntPtr token)
    {
        var identity = new WindowsIdentity(token);
        return identity.Impersonate();
    }

    private static IntPtr GetPrimaryToken(Process process)
    {
        var token = IntPtr.Zero;
        var primaryToken = IntPtr.Zero;

        if (OpenProcessToken(process.Handle, TOKEN_DUPLICATE, ref token))
        {
            var sa = new SECURITY_ATTRIBUTES();
            sa.nLength = Marshal.SizeOf(sa);

            if (!DuplicateTokenEx(
                token,
                TOKEN_ALL_ACCESS,
                ref sa,
                (int)SECURITY_IMPERSONATION_LEVEL.SecurityImpersonation,
                (int)TOKEN_TYPE.TokenPrimary,
                ref primaryToken))
            {
                throw new Win32Exception(Marshal.GetLastWin32Error(), "DuplicateTokenEx failed");
            }

            CloseHandle(token);
        }
        else
        {
            throw new Win32Exception(Marshal.GetLastWin32Error(), "OpenProcessToken failed");
        }

        return primaryToken;
    }

    public static IntPtr GetEnvironmentBlock(IntPtr token)
    {
        var envBlock = IntPtr.Zero;
        if (!CreateEnvironmentBlock(ref envBlock, token, false))
        {
            throw new Win32Exception(Marshal.GetLastWin32Error(), "CreateEnvironmentBlock failed");
        }
        return envBlock;
    }

    public static void LaunchAsCurrentUser(string cmdLine)
    {
        var process = Process.GetProcessesByName("explorer").FirstOrDefault();
        if (process != null)
        {
            var token = GetPrimaryToken(process);
            if (token != IntPtr.Zero)
            {
                var envBlock = GetEnvironmentBlock(token);
                if (envBlock != IntPtr.Zero)
                {
                    LaunchProcessAsUser(cmdLine, token, envBlock, process.SessionId);
                    if (!DestroyEnvironmentBlock(envBlock))
                    {
                        throw new Win32Exception(Marshal.GetLastWin32Error(), "DestroyEnvironmentBlock failed");
                    }
                }

                CloseHandle(token);
            }
        }
    }

    //Methode de lancement de commande impersonatée avec un user typé Domain

    public static void LaunchAsDomainUser(string cmdLine, String UserName, String Password, String Domain)
    {
        SafeTokenHandle safeTokenHandle;
        bool returnValue = LogonUser(UserName, Domain, Password,
        (int)LogonTypes.Interactive, (int)LogonProvider.LOGON32_PROVIDER_DEFAULT,
            out safeTokenHandle);

        using (WindowsIdentity newId = new WindowsIdentity(safeTokenHandle.DangerousGetHandle()))
        {
            using (WindowsImpersonationContext impersonatedUser = newId.Impersonate())
            {
                LaunchAsCurrentUser(cmdLine);
            }
        }
    }

    //Methode de lancement de commande impersonatée avec un user typé Local

    public static void LaunchAsLocalUser(string cmdLine, String UserName, String Password)
    {
        var envBlock = IntPtr.Zero;
        var token = IntPtr.Zero;

        bool returnValue = LogonUser(UserName, ".", Password,
            (int)LogonTypes.Batch, (int)LogonProvider.LOGON32_PROVIDER_DEFAULT,
            ref token);

        envBlock = ImpersonationUtils.GetEnvironmentBlock(token);
        var process = Process.GetProcessesByName("explorer").FirstOrDefault();
        LaunchProcessAsUser(cmdLine, token, envBlock, process.SessionId);
        CloseHandle(token);
    }

    //Classe de génération de handle typé SafeTokenHandle

    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);
        }
    }

    public static IDisposable ImpersonateCurrentUser()
    {
        var process = Process.GetProcessesByName("explorer").FirstOrDefault();
        if (process != null)
        {
            var token = GetPrimaryToken(process);
            if (token != IntPtr.Zero)
            {
                return Impersonate(token);
            }
        }

        throw new Exception("Could not find explorer.exe");
    }
}

After this, from your page code, you can run :

• For Domain accounts : ImpersonationUtils.LaunchAsDomainUser("BlaBla cmd code", UserName, Password, Domain);

• For Local Accounts : ImpersonationUtils.LaunchAsLocalUser("BlaBla cmd code", UserName, Password);

I hope it will help

Simulate

public static void LaunchAsDomainUser(string cmdLine, String UserName, String Password, String Domain) { SafeTokenHandle safeTokenHandle; bool returnValue = LogonUser(UserName, Domain, Password, (int)LogonTypes.Batch, (int)LogonProvider.LOGON32_PROVIDER_DEFAULT, out safeTokenHandle); using (WindowsIdentity newId = new WindowsIdentity(safeTokenHandle.DangerousGetHandle())) { using (WindowsImpersonationContext impersonatedUser = newId.Impersonate()) { LaunchAsCurrentUser(cmdLine); } } } – Simulate

ACCESS is DENIED @frido – Shakira