Develop Reference

Standard output from CreateProcessAsUser Always Empty in C#

The first Call to Launch Method Write Into file echo1, but I can't capture the standard output of the second line of the test, what I am doing wrong?
[TestMethod]
public void Launch()
{
var resp = ProcessAsUserTest.ProcessAsUser.Launch("cmd.exe /c \"echo 1\" >> c:\\temp\\echo1");
var resp1 = ProcessAsUserTest.ProcessAsUser.Launch("cmd.exe /c \"echo 1\"");
Assert.AreEqual("1", resp1);
}
I was follow this thread but It has not answer: Capture standard output from CreateProcessAsUser in C#
I get the implementation from https://social.msdn.microsoft.com/Forums/vstudio/en-US/0c0ca087-5e7b-4046-93cb-c7b3e48d0dfb/how-run-client-application-as-a-windows-service-in-c?forum=csharpgeneral
and I've edited the code to get standard output same as the first link without answer.
Here the implementation:
using Microsoft.Win32.SafeHandles;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
namespace ProcessAsUserTest
{
[StructLayout(LayoutKind.Sequential)]
internal struct PROCESS_INFORMATION
{
public IntPtr hProcess;
public IntPtr hThread;
public uint dwProcessId;
public uint dwThreadId;
}
[StructLayout(LayoutKind.Sequential)]
internal struct SECURITY_ATTRIBUTES
{
public uint nLength;
public IntPtr lpSecurityDescriptor;
public bool bInheritHandle;
}
[StructLayout(LayoutKind.Sequential)]
public struct STARTUPINFO
{
public uint cb;
public string lpReserved;
public string lpDesktop;
public string lpTitle;
public uint dwX;
public uint dwY;
public uint dwXSize;
public uint dwYSize;
public uint dwXCountChars;
public uint dwYCountChars;
public uint dwFillAttribute;
public uint dwFlags;
public short wShowWindow;
public short cbReserved2;
public IntPtr lpReserved2;
public IntPtr hStdInput;
public IntPtr hStdOutput;
public IntPtr hStdError;
}
internal enum SECURITY_IMPERSONATION_LEVEL
{
SecurityAnonymous,
SecurityIdentification,
SecurityImpersonation,
SecurityDelegation
}
internal enum TOKEN_TYPE
{
TokenPrimary = 1,
TokenImpersonation
}
[Flags]
enum HANDLE_FLAGS
{
INHERIT = 1,
}
public class ProcessAsUser
{
[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,
uint dwCreationFlags,
IntPtr lpEnvironment,
string lpCurrentDirectory,
ref STARTUPINFO lpStartupInfo,
out PROCESS_INFORMATION lpProcessInformation);
[DllImport("advapi32.dll", EntryPoint = "DuplicateTokenEx", SetLastError = true)]
private static extern bool DuplicateTokenEx(
IntPtr hExistingToken,
uint dwDesiredAccess,
ref SECURITY_ATTRIBUTES lpThreadAttributes,
Int32 ImpersonationLevel,
Int32 dwTokenType,
ref IntPtr phNewToken);
[DllImport("advapi32.dll", SetLastError = true)]
private static extern bool OpenProcessToken(
IntPtr ProcessHandle,
UInt32 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("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr CreateNamedPipe(string name, int openMode, int pipeMode, int maxInstances, int outBufSize, int inBufSize, int timeout, IntPtr lpPipeAttributes);
[DllImport("kernel32.dll", CharSet = CharSet.Auto)]
private static extern IntPtr CreateFile(string lpFileName, int dwDesiredAccess, int dwShareMode, IntPtr lpSecurityAttributes, int dwCreationDisposition, int dwFlagsAndAttributes, HandleRef hTemplateFile);
[DllImport("kernel32.dll", CharSet = CharSet.Ansi, SetLastError = true)]
private static extern IntPtr GetStdHandle(int whichHandle);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool GetExitCodeProcess(IntPtr process, ref UInt32 exitCode);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool SetHandleInformation(IntPtr hObject, HANDLE_FLAGS dwMask, HANDLE_FLAGS dwFlags);
[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
public static extern int GetConsoleOutputCP();
[DllImport("kernel32.dll")]
static extern int WaitForSingleObject(IntPtr hHandle, int dwMilliseconds);
private const short SW_SHOW = 5;
private const short SW_HIDE = 0;
private const uint TOKEN_QUERY = 0x0008;
private const uint TOKEN_DUPLICATE = 0x0002;
private const uint TOKEN_ASSIGN_PRIMARY = 0x0001;
private const int GENERIC_ALL_ACCESS = 0x10000000;
private const int STARTF_USESHOWWINDOW = 0x00000001;
private const int STARTF_FORCEONFEEDBACK = 0x00000040;
private const uint CREATE_UNICODE_ENVIRONMENT = 0x00000400;
private const int STD_INPUT_HANDLE = -10;
private static readonly IntPtr INVALID_HANDLE_VALUE = (IntPtr)(-1);
private static readonly HandleRef NullHandleRef = new HandleRef(null, IntPtr.Zero);
private static string LaunchProcessAsUser(string cmdLine, IntPtr token, IntPtr envBlock)
{
bool result = false;
PROCESS_INFORMATION pi = new PROCESS_INFORMATION();
SECURITY_ATTRIBUTES saProcess = new SECURITY_ATTRIBUTES();
SECURITY_ATTRIBUTES saThread = new SECURITY_ATTRIBUTES();
saProcess.nLength = (uint)Marshal.SizeOf(saProcess);
saThread.nLength = (uint)Marshal.SizeOf(saThread);
IntPtr stdoutReadHandle = IntPtr.Zero;
SafeFileHandle safeHandle = null;
IntPtr stdoutWriteHandle = IntPtr.Zero;
IntPtr stdinHandle = GetStdHandle(STD_INPUT_HANDLE);
try
{
CreatePipe(out stdoutReadHandle, out stdoutWriteHandle, false);
SetHandleInformation(stdoutReadHandle, HANDLE_FLAGS.INHERIT, 0);
STARTUPINFO si = new STARTUPINFO();
si.cb = (uint)Marshal.SizeOf(si);
//if this member is NULL, the new process inherits the desktop
//and window station of its parent process. If this member is
//an empty string, the process does not inherit the desktop and
//window station of its parent process; instead, the system
//determines if a new desktop and window station need to be created.
//If the impersonated user already has a desktop, the system uses the
//existing desktop.
si.lpDesktop = #"WinSta0\Default"; //Modify as needed
si.dwFlags = STARTF_USESHOWWINDOW | STARTF_FORCEONFEEDBACK;
si.wShowWindow = SW_SHOW;
si.hStdInput = stdinHandle;
si.hStdOutput = stdoutWriteHandle;
si.hStdOutput = stdoutWriteHandle;
//Set other si properties as required.
result = CreateProcessAsUser(
token,
null,
cmdLine,
ref saProcess,
ref saThread,
false,
CREATE_UNICODE_ENVIRONMENT,
envBlock,
null,
ref si,
out pi);
if (result == false)
{
int error = Marshal.GetLastWin32Error();
string message = String.Format("CreateProcessAsUser Error: {0}", error);
Debug.WriteLine(message);
}
var ret = WaitForSingleObject(pi.hProcess, 100000);
//Console.Write("WaitForSingleObject returned " + ret);
//ret==258 (0x102) - not signalled, ret==0 ok!
CloseHandle(pi.hProcess);
CloseHandle(pi.hThread);
CloseHandle(stdoutWriteHandle);
CloseHandle(stdinHandle);
safeHandle = new SafeFileHandle(stdoutReadHandle, true);
string outputData;
var encoding = Encoding.GetEncoding(GetConsoleOutputCP());
using (var fs = new FileStream(safeHandle, FileAccess.Read, 0x1000, true))
using (var reader = new StreamReader(fs, encoding))
{
outputData = reader.ReadToEnd();
}
return outputData;
}
finally
{
if (!safeHandle.IsClosed)
{
safeHandle.Close();
}
}
}
private static IntPtr GetPrimaryToken(int processId)
{
IntPtr token = IntPtr.Zero;
IntPtr primaryToken = IntPtr.Zero;
bool retVal = false;
Process p = null;
try
{
p = Process.GetProcessById(processId);
}
catch (ArgumentException ex)
{
string details = String.Format("ProcessID {0} Not Available, More: {1}", processId, ex.Message);
throw new ArgumentException(details);
}
//Gets impersonation token
retVal = OpenProcessToken(p.Handle, TOKEN_DUPLICATE, ref token);
if (retVal == true)
{
SECURITY_ATTRIBUTES sa = new SECURITY_ATTRIBUTES();
sa.nLength = (uint)Marshal.SizeOf(sa);
//Convert the impersonation token into Primary token
retVal = DuplicateTokenEx(
token,
TOKEN_ASSIGN_PRIMARY | TOKEN_DUPLICATE | TOKEN_QUERY,
ref sa,
(int)SECURITY_IMPERSONATION_LEVEL.SecurityIdentification,
(int)TOKEN_TYPE.TokenPrimary,
ref primaryToken);
//Close the Token that was previously opened.
CloseHandle(token);
if (retVal == false)
{
string message = String.Format("DuplicateTokenEx Error: {0}", Marshal.GetLastWin32Error());
throw new Exception(message);
}
}
else
{
string message = String.Format("OpenProcessToken Error: {0}", Marshal.GetLastWin32Error());
Debug.WriteLine(message);
}
//We'll Close this token after it is used.
return primaryToken;
}
private static IntPtr GetEnvironmentBlock(IntPtr token)
{
IntPtr envBlock = IntPtr.Zero;
bool retVal = CreateEnvironmentBlock(ref envBlock, token, false);
if (retVal == false)
{
//Environment Block, things like common paths to My Documents etc.
//Will not be created if "false"
//It should not adversley affect CreateProcessAsUser.
string message = String.Format("CreateEnvironmentBlock Error: {0}", Marshal.GetLastWin32Error());
Debug.WriteLine(message);
}
return envBlock;
}
public static string Launch(string appCmdLine /*,int processId*/)
{
string ret = "";
//Either specify the processID explicitly
//Or try to get it from a process owned by the user.
//In this case assuming there is only one explorer.exe
Process[] ps = Process.GetProcessesByName("explorer");
int processId = -1;//=processId
if (ps.Length > 0)
{
processId = ps[0].Id;
}
if (processId > 1)
{
IntPtr token = GetPrimaryToken(processId);
if (token != IntPtr.Zero)
{
IntPtr envBlock = GetEnvironmentBlock(token);
ret = LaunchProcessAsUser(appCmdLine, token, envBlock);
if (envBlock != IntPtr.Zero)
DestroyEnvironmentBlock(envBlock);
CloseHandle(token);
}
}
return ret;
}
private static void CreatePipe(out IntPtr parentHandle, out IntPtr childHandle, bool parentInputs)
{
string pipename = #"\\.\pipe\" + Guid.NewGuid().ToString();
parentHandle = CreateNamedPipe(pipename, 0x40000003, 0, 0xff, 0x1000, 0x1000, 0, IntPtr.Zero);
if (parentHandle == INVALID_HANDLE_VALUE)
{
throw new Exception("Invalid Handle Exception.");
}
int childAcc = 0x40000000;
if (parentInputs)
{
childAcc = -2147483648;
}
childHandle = CreateFile(pipename, childAcc, 3, IntPtr.Zero, 3, 0x40000080, NullHandleRef);
if (childHandle == INVALID_HANDLE_VALUE)
{
throw new Exception("Invalid Handle Exception.");
}
}
}
}
NOTE: It is a sample code only, In real code I want to take a screenshot of the desktop from Window Service using another process, In the context of explorer.exe, because windows service cannot access to desktop directly and need another context to do it.
Same thread:https://social.msdn.microsoft.com/Forums/vstudio/en-US/19ff0bb0-924f-4f9c-9b71-ff4ee4ccaf50/standard-output-from-createprocessasuser-always-empty-in-c?forum=csharpgeneral#19ff0bb0-924f-4f9c-9b71-ff4ee4ccaf50
If you need more information please tell me, thanks!

Error 6 when injecting DLL using C#

when I try to inject a DLL with C# into a java process (Minecraft specifically) I get an error "ERROR 6", I've been googling this error but couldnt find a solution.
The program is run in administrator mode, and it isnt trying to load from an admin path.
My code:
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Text;
namespace Launcher
{
internal class InjectionUtils
{
public struct CTX_PROCS
{
public Process[] procs;
}
private const int PROCESS_CREATE_THREAD = 2;
private const int PROCESS_QUERY_INFORMATION = 1024;
private const int PROCESS_VM_OPERATION = 8;
private const int PROCESS_VM_WRITE = 32;
private const int PROCESS_VM_READ = 16;
private const uint MEM_COMMIT = 4096u;
private const uint MEM_RESERVE = 8192u;
private const uint PAGE_READWRITE = 4u;
[DllImport("kernel32.dll")]
public static extern IntPtr OpenProcess(int dwDesiredAccess, bool bInheritHandle, int dwProcessId);
[DllImport("kernel32.dll", CharSet = CharSet.Auto)]
public static extern IntPtr GetModuleHandle(string lpModuleName);
[DllImport("kernel32", CharSet = CharSet.Ansi, ExactSpelling = true, SetLastError = true)]
private static extern IntPtr GetProcAddress(IntPtr hModule, string procName);
[DllImport("kernel32.dll", ExactSpelling = true, SetLastError = true)]
private static extern IntPtr VirtualAllocEx(IntPtr hProcess, IntPtr lpAddress, uint dwSize, uint flAllocationType, uint flProtect);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool WriteProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, byte[] lpBuffer, uint nSize, out UIntPtr lpNumberOfBytesWritten);
[DllImport("kernel32.dll")]
private static extern IntPtr CreateRemoteThread(IntPtr hProcess, IntPtr lpThreadAttributes, uint dwStackSize, IntPtr lpStartAddress, IntPtr lpParameter, uint dwCreationFlags, IntPtr lpThreadId);
[DllImport("user32.dll", CharSet = CharSet.Auto)]
private static extern int MessageBox(IntPtr hWnd, string text, string caption, uint option);
[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool CloseHandle(IntPtr hObject);
[DllImport("kernel32.dll")]
private static extern uint GetLastError();
private void MBox(string text)
{
InjectionUtils.MessageBox(IntPtr.Zero, text, "", 0u);
}
public void DoInjection(string dllPath)
{
InjectionUtils.CTX_PROCS cTX_PROCS = this.FindProcessByNameAndTitle("javaw", "Minecraft 1.7");
this.InjectDynamicLib(dllPath, cTX_PROCS.procs[0].Id);
}
public InjectionUtils.CTX_PROCS FindProcessByNameAndTitle(string processName, string title)
{
InjectionUtils.CTX_PROCS result = default(InjectionUtils.CTX_PROCS);
List<Process> list = new List<Process>();
Process[] processes = Process.GetProcesses();
for (int i = 0; i < processes.Length; i++)
{
Process process = processes[i];
if (process.ProcessName.Equals(processName) && process.MainWindowTitle.Contains(title))
{
list.Add(process);
}
}
result.procs = list.ToArray();
return result;
}
public void eject()
{
}
private bool InjectDynamicLib(string dllPath, int pId)
{
bool result = false;
IntPtr intPtr = InjectionUtils.OpenProcess(1082, false, pId);
uint num = (uint)((dllPath.Length + 1) * Marshal.SizeOf(typeof(char)));
if (intPtr != IntPtr.Zero)
{
IntPtr procAddress = InjectionUtils.GetProcAddress(InjectionUtils.GetModuleHandle("kernel32.dll"), "LoadLibraryA");
IntPtr intPtr2 = InjectionUtils.VirtualAllocEx(intPtr, IntPtr.Zero, num, 12288u, 4u);
UIntPtr uIntPtr;
// Write path of dll to remote process
if (InjectionUtils.WriteProcessMemory(intPtr, intPtr2, Encoding.Default.GetBytes(dllPath), num, out uIntPtr))
{
InjectionUtils.CloseHandle(InjectionUtils.CreateRemoteThread(intPtr, IntPtr.Zero, 0u, procAddress, intPtr2, 0u, IntPtr.Zero));
result = true;
}
InjectionUtils.CloseHandle(intPtr);
}
if (InjectionUtils.GetLastError() != 0u)
{
this.MBox("ERROR " + InjectionUtils.GetLastError());
}
return result;
}
If anyone could help I would appreciate it dearly :)
Thanks in advance :D

From MSDN Error Code List:
ERROR_INVALID_HANDLE
0x6
Before you call GetLastError() you call CloseHandle() twice, once on the thread handle and on the process handle.
To find the problem just check the returns from OpenProcess() and CreateRemoteThread() and compare against the info you find in the functions documentation on MSDN.
For a simple no frills C# injector, this is the code I like to use which includes some error checking and uses the managed Process::Dispose() method instead of calling the native CloseHandle() at least on the process handle:
public static bool InjectDLL(string dllpath, string procname)
{
Process[] procs = Process.GetProcessesByName(Path.GetFileNameWithoutExtension(procname));
if (procs.Length == 0)
{
return false;
}
Process proc = procs[0];
if (proc.Handle != IntPtr.Zero)
{
IntPtr loc = VirtualAllocEx(proc.Handle, IntPtr.Zero, MAX_PATH, AllocationType.Commit | AllocationType.Reserve,
MemoryProtection.ReadWrite);
if (loc.Equals(0))
{
return false;
}
IntPtr bytesRead = IntPtr.Zero;
bool result = WriteProcessMemory(proc.Handle, loc, dllpath.ToCharArray(), dllpath.Length, out bytesRead);
if (!result || bytesRead.Equals(0))
{
return false;
}
IntPtr loadlibAddy = GetProcAddress(GetModuleHandle("kernel32.dll"), "LoadLibraryA");
IntPtr hThread = CreateRemoteThread(proc.Handle, IntPtr.Zero, 0, loadlibAddy, loc, 0, out _);
if (!hThread.Equals(0))
{
CloseHandle(hThread);
}
else return false;
}
else return false;
//this will CloseHandle automatically using the managed method
proc.Dispose();
return true;
}
Make sure to run as admin and pinvoke any missing definitions.

Reading from Protected Process Memory

I'm trying to read the memory of a process.
The actual code loops through the process' memory and searches for values but this is the general idea.
I'm compiling for x64 and attempting to read x64 processes.
This code fails after the call to VirtualProtectEx with either error code 5 (ERROR_ACCESS_DENIED) or error code 487 (ERROR_INVALID_ADDRESS) depending on the process selected.
Am I reading the process' memory in the correct way?
How can VirtualProtectEx fail with access denied?
Are there other protection methods I haven't considered?
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Security.Principal;
namespace ReadProcessMemoryTest {
public class Program {
public static void Main(string[] args) {
string processName = "ProcessName";
IntPtr startAddress = new IntPtr(0x00000000);
IntPtr endAddress = new IntPtr(0x7FFFFFFF);
uint bytesToRead = 8;
int errorCode = 0;
// Ensure running as admin
WindowsIdentity identity = WindowsIdentity.GetCurrent();
WindowsPrincipal principal = new WindowsPrincipal(identity);
if(!principal.IsInRole(WindowsBuiltInRole.Administrator)){
throw new Exception("Not running as administrator");
}
// Turn on SeDebugPrivilege
Process.EnterDebugMode();
// Select the process
Process process = Process.GetProcessesByName(processName)[0];
// Get a handle to the process with all access rights
IntPtr processHandle = OpenProcess(0x001F0FFF, 1, (uint)process.Id);
// Check for errors
errorCode = Marshal.GetLastWin32Error();
if(errorCode != 0) {
throw new Exception("OpenProcess error: " + errorCode);
}
// Set the protection level of these 8 bytes to execute, read and write
uint prevProtection = 0;
VirtualProtectEx(processHandle, startAddress, new UIntPtr(bytesToRead), 0x40, out prevProtection);
// Check for errors
errorCode = Marshal.GetLastWin32Error();
if(errorCode != 0) {
throw new Exception("VirtualProtectEx error: " + errorCode);
}
// Read some bytes into an array
byte[] buffer = new byte[bytesToRead];
IntPtr bytesRead;
ReadProcessMemory(processHandle, startAddress, buffer, bytesToRead, out bytesRead);
// Check for errors
errorCode = Marshal.GetLastWin32Error();
if(errorCode != 0) {
throw new Exception("ReadProcessMemory error: " + errorCode);
}
// Close the process handle
CloseHandle(processHandle);
}
[DllImport("kernel32.dll", SetLastError = true)]
public static extern IntPtr OpenProcess(UInt32 dwDesiredAccess, Int32 bInheritHandle, UInt32 dwProcessId);
[DllImport("kernel32.dll")]
public static extern Int32 CloseHandle(IntPtr hObject);
[DllImport("kernel32.dll", SetLastError = true)]
public static extern Int32 VirtualProtectEx(IntPtr hProcess, IntPtr lpAddress, UIntPtr dwSize, uint flNewProtect, out uint lpflOldProtect);
[DllImport("kernel32.dll", SetLastError = true)]
public static extern Int32 ReadProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, [In, Out] byte[] buffer, UInt32 size, out IntPtr lpNumberOfBytesRead);
}
}

EnterDebugMode() is not enough, you need to explicitly AdjustTokenPrivileges
using System;
using System.Runtime.InteropServices;
public class TokenManipulator
{
[DllImport("advapi32.dll", ExactSpelling = true, SetLastError = true)]
internal static extern bool AdjustTokenPrivileges(IntPtr htok, bool disall,
ref TokPriv1Luid newst, int len, IntPtr prev, IntPtr relen);
[DllImport("kernel32.dll", ExactSpelling = true)]
internal static extern IntPtr GetCurrentProcess();
[DllImport("advapi32.dll", ExactSpelling = true, SetLastError = true)]
internal static extern bool OpenProcessToken(IntPtr h, int acc, ref IntPtr phtok);
[DllImport("advapi32.dll", SetLastError = true)]
internal static extern bool LookupPrivilegeValue(string host, string name, ref long pluid);
[StructLayout(LayoutKind.Sequential, Pack = 1)]
internal struct TokPriv1Luid
{
public int Count;
public long Luid;
public int Attr;
}
internal const int SE_PRIVILEGE_DISABLED = 0x00000000;
internal const int SE_PRIVILEGE_ENABLED = 0x00000002;
internal const int TOKEN_QUERY = 0x00000008;
internal const int TOKEN_ADJUST_PRIVILEGES = 0x00000020;
public static bool AddPrivilege(string privilege)
{
try
{
bool retVal;
TokPriv1Luid tp;
IntPtr hproc = GetCurrentProcess();
IntPtr htok = IntPtr.Zero;
retVal = OpenProcessToken(hproc, TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY, ref htok);
tp.Count = 1;
tp.Luid = 0;
tp.Attr = SE_PRIVILEGE_ENABLED;
retVal = LookupPrivilegeValue(null, privilege, ref tp.Luid);
retVal = AdjustTokenPrivileges(htok, false, ref tp, 0, IntPtr.Zero, IntPtr.Zero);
return retVal;
}
catch (Exception ex)
{
throw ex;
}
}

Read other process current directory in C#

I am trying to get current working directory of selected process. I am sure that it is possible, because tools like Process Explorer can show this information. I found out that this information is stored in PEB.
Moreover I found Oleksiy blog post: http://eazfuscator.blogspot.com/2011/06/reading-environment-variables-from.html, but all my modifications are totally unless.
So my question is how can I read this information in C#? If Oleksiy code is a good way, how should I modify his code to get this information?

As other pointed out, this is completely undocumented, but here is a piece of code that does it (as of today, it seems to work). Of course, it needs to run as admin. Note it can work for any process bitness, 32-bit or 64-bit (some processess may report an access denied, even running as admin), with any compilation target (x86 or x64). It also is capable of reading the command line. Use at your own risk!
// All offset values below have been tested on Windows 7 & 8 only
// but you can use WinDbg "dt ntdll!_PEB" command and search for ProcessParameters offset to find the truth, depending on the OS version
public static class ProcessUtilities
{
public static string GetCurrentDirectory(int processId)
{
return GetProcessParametersString(processId, Environment.Is64BitOperatingSystem ? 0x38 : 0x24);
}
public static string GetCurrentDirectory(this Process process)
{
if (process == null)
throw new ArgumentNullException("process");
return GetCurrentDirectory(process.Id);
}
public static string GetCommandLine(int processId)
{
return GetProcessParametersString(processId, Environment.Is64BitOperatingSystem ? 0x70 : 0x40);
}
public static string GetCommandLine(this Process process)
{
if (process == null)
throw new ArgumentNullException("process");
return GetCommandLine(process.Id);
}
private static string GetProcessParametersString(int processId, int offset)
{
IntPtr handle = OpenProcess(PROCESS_QUERY_INFORMATION | PROCESS_VM_READ, false, processId);
if (handle == IntPtr.Zero)
throw new Win32Exception(Marshal.GetLastWin32Error());
int processParametersOffset = Environment.Is64BitOperatingSystem ? 0x20 : 0x10;
try
{
if (Environment.Is64BitOperatingSystem && !Environment.Is64BitProcess) // are we running in WOW?
{
PROCESS_BASIC_INFORMATION_WOW64 pbi = new PROCESS_BASIC_INFORMATION_WOW64();
int hr = NtWow64QueryInformationProcess64(handle, 0, ref pbi, Marshal.SizeOf(pbi), IntPtr.Zero);
if (hr != 0)
throw new Win32Exception(hr);
long pp = 0;
hr = NtWow64ReadVirtualMemory64(handle, pbi.PebBaseAddress + processParametersOffset, ref pp, Marshal.SizeOf(pp), IntPtr.Zero);
if (hr != 0)
throw new Win32Exception(hr);
UNICODE_STRING_WOW64 us = new UNICODE_STRING_WOW64();
hr = NtWow64ReadVirtualMemory64(handle, pp + offset, ref us, Marshal.SizeOf(us), IntPtr.Zero);
if (hr != 0)
throw new Win32Exception(hr);
if ((us.Buffer == 0) || (us.Length == 0))
return null;
string s = new string('\0', us.Length / 2);
hr = NtWow64ReadVirtualMemory64(handle, us.Buffer, s, us.Length, IntPtr.Zero);
if (hr != 0)
throw new Win32Exception(hr);
return s;
}
else // we are running with the same bitness as the OS, 32 or 64
{
PROCESS_BASIC_INFORMATION pbi = new PROCESS_BASIC_INFORMATION();
int hr = NtQueryInformationProcess(handle, 0, ref pbi, Marshal.SizeOf(pbi), IntPtr.Zero);
if (hr != 0)
throw new Win32Exception(hr);
IntPtr pp = new IntPtr();
if (!ReadProcessMemory(handle, pbi.PebBaseAddress + processParametersOffset, ref pp, new IntPtr(Marshal.SizeOf(pp)), IntPtr.Zero))
throw new Win32Exception(Marshal.GetLastWin32Error());
UNICODE_STRING us = new UNICODE_STRING();
if (!ReadProcessMemory(handle, pp + offset, ref us, new IntPtr(Marshal.SizeOf(us)), IntPtr.Zero))
throw new Win32Exception(Marshal.GetLastWin32Error());
if ((us.Buffer == IntPtr.Zero) || (us.Length == 0))
return null;
string s = new string('\0', us.Length / 2);
if (!ReadProcessMemory(handle, us.Buffer, s, new IntPtr(us.Length), IntPtr.Zero))
throw new Win32Exception(Marshal.GetLastWin32Error());
return s;
}
}
finally
{
CloseHandle(handle);
}
}
private const int PROCESS_QUERY_INFORMATION = 0x400;
private const int PROCESS_VM_READ = 0x10;
[StructLayout(LayoutKind.Sequential)]
private struct PROCESS_BASIC_INFORMATION
{
public IntPtr Reserved1;
public IntPtr PebBaseAddress;
public IntPtr Reserved2_0;
public IntPtr Reserved2_1;
public IntPtr UniqueProcessId;
public IntPtr Reserved3;
}
[StructLayout(LayoutKind.Sequential)]
private struct UNICODE_STRING
{
public short Length;
public short MaximumLength;
public IntPtr Buffer;
}
// for 32-bit process in a 64-bit OS only
[StructLayout(LayoutKind.Sequential)]
private struct PROCESS_BASIC_INFORMATION_WOW64
{
public long Reserved1;
public long PebBaseAddress;
public long Reserved2_0;
public long Reserved2_1;
public long UniqueProcessId;
public long Reserved3;
}
// for 32-bit process in a 64-bit OS only
[StructLayout(LayoutKind.Sequential)]
private struct UNICODE_STRING_WOW64
{
public short Length;
public short MaximumLength;
public long Buffer;
}
[DllImport("ntdll.dll")]
private static extern int NtQueryInformationProcess(IntPtr ProcessHandle, int ProcessInformationClass, ref PROCESS_BASIC_INFORMATION ProcessInformation, int ProcessInformationLength, IntPtr ReturnLength);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool ReadProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, ref IntPtr lpBuffer, IntPtr dwSize, IntPtr lpNumberOfBytesRead);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool ReadProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, ref UNICODE_STRING lpBuffer, IntPtr dwSize, IntPtr lpNumberOfBytesRead);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool ReadProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, [MarshalAs(UnmanagedType.LPWStr)] string lpBuffer, IntPtr dwSize, IntPtr lpNumberOfBytesRead);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern IntPtr OpenProcess(int dwDesiredAccess, bool bInheritHandle, int dwProcessId);
[DllImport("kernel32.dll")]
private static extern bool CloseHandle(IntPtr hObject);
// for 32-bit process in a 64-bit OS only
[DllImport("ntdll.dll")]
private static extern int NtWow64QueryInformationProcess64(IntPtr ProcessHandle, int ProcessInformationClass, ref PROCESS_BASIC_INFORMATION_WOW64 ProcessInformation, int ProcessInformationLength, IntPtr ReturnLength);
[DllImport("ntdll.dll")]
private static extern int NtWow64ReadVirtualMemory64(IntPtr hProcess, long lpBaseAddress, ref long lpBuffer, long dwSize, IntPtr lpNumberOfBytesRead);
[DllImport("ntdll.dll")]
private static extern int NtWow64ReadVirtualMemory64(IntPtr hProcess, long lpBaseAddress, ref UNICODE_STRING_WOW64 lpBuffer, long dwSize, IntPtr lpNumberOfBytesRead);
[DllImport("ntdll.dll")]
private static extern int NtWow64ReadVirtualMemory64(IntPtr hProcess, long lpBaseAddress, [MarshalAs(UnmanagedType.LPWStr)] string lpBuffer, long dwSize, IntPtr lpNumberOfBytesRead);
}

"Simon Mourier" source are work fine in OS,Executor,Target is 32bit. But others are not.
So I Add source to handle all combination of 32, 64bit.
There are 5 possible combination of 32, 64bit process.
First, os,executor,target are 32bit. Second, os is 64bit, executor, target are combination of 32,64bit process.
This code is work fine in My notebook Win7 64Bit OS, 32,64bit Process & target 32,64bit Process, WinXp 32bit , exeutor,target are 32bit. But, Use at your own risk!
// ref: http://www.microsoft.com/whdc/system/Sysinternals/MoreThan64proc.mspx
public enum PROCESSINFOCLASS : int
{
ProcessBasicInformation = 0, // 0, q: PROCESS_BASIC_INFORMATION, PROCESS_EXTENDED_BASIC_INFORMATION
ProcessWow64Information = 26, // q: ULONG_PTR
}
[Flags]
public enum PEB_OFFSET
{
CurrentDirectory,
//DllPath,
//ImagePathName,
CommandLine,
//WindowTitle,
//DesktopInfo,
//ShellInfo,
//RuntimeData,
//TypeMask = 0xffff,
//Wow64 = 0x10000,
};
public class Is64BitChecker
{
[DllImport("kernel32.dll", SetLastError = true, CallingConvention = CallingConvention.Winapi)]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool IsWow64Process(
[In] IntPtr hProcess,
[Out] out bool wow64Process
);
public static bool GetProcessIsWow64(IntPtr hProcess)
{
if ((Environment.OSVersion.Version.Major == 5 && Environment.OSVersion.Version.Minor >= 1) ||
Environment.OSVersion.Version.Major >= 6)
{
bool retVal;
if (!IsWow64Process(hProcess, out retVal))
{
return false;
}
return retVal;
}
else
{
return false;
}
}
public static bool InternalCheckIsWow64()
{
if ((Environment.OSVersion.Version.Major == 5 && Environment.OSVersion.Version.Minor >= 1) ||
Environment.OSVersion.Version.Major >= 6)
{
using (Process p = Process.GetCurrentProcess())
{
bool retVal;
if (!IsWow64Process(p.Handle, out retVal))
{
return false;
}
return retVal;
}
}
else
{
return false;
}
}
}
// All offset values below have been tested on Windows 7 & 8 only
// but you can use WinDbg "dt ntdll!_PEB" command and search for ProcessParameters offset to find the truth, depending on the OS version
public static class ProcessUtilities
{
public static readonly bool Is64BitProcess = IntPtr.Size > 4;
public static readonly bool Is64BitOperatingSystem = Is64BitProcess || Is64BitChecker.InternalCheckIsWow64();
public static string GetCurrentDirectory(int processId)
{
return GetProcessParametersString(processId, PEB_OFFSET.CurrentDirectory);
}
public static string GetCurrentDirectory(this Process process)
{
if (process == null)
throw new ArgumentNullException("process");
return GetCurrentDirectory(process.Id);
}
#region GetCommandLine
//public static string GetCommandLine(int processId)
//{
// return null;// GetProcessParametersString(processId, Is64BitOperatingSystem ? 0x70 : 0x40);
//}
//public static string GetCommandLine(this Process process)
//{
// if (process == null)
// throw new ArgumentNullException("process");
// return GetCommandLine(process.Id);
//}
#endregion
private static string GetProcessParametersString(int processId, PEB_OFFSET Offset)
{
IntPtr handle = OpenProcess(PROCESS_QUERY_INFORMATION | PROCESS_VM_READ, false, processId);
if (handle == IntPtr.Zero)
throw new Win32Exception(Marshal.GetLastWin32Error());
bool IsWow64Process = Is64BitChecker.InternalCheckIsWow64();
bool IsTargetWow64Process = Is64BitChecker.GetProcessIsWow64(handle);
bool IsTarget64BitProcess = Is64BitOperatingSystem && !IsTargetWow64Process;
long offset = 0;
long processParametersOffset = IsTarget64BitProcess ? 0x20 : 0x10;
switch (Offset)
{
case PEB_OFFSET.CurrentDirectory:
offset = IsTarget64BitProcess ? 0x38 : 0x24;
break;
case PEB_OFFSET.CommandLine:
default:
return null;
}
try
{
long pebAddress = 0;
if (IsTargetWow64Process) // OS : 64Bit, Cur : 32 or 64, Tar: 32bit
{
IntPtr peb32 = new IntPtr();
int hr = NtQueryInformationProcess(handle, (int)PROCESSINFOCLASS.ProcessWow64Information, ref peb32, IntPtr.Size, IntPtr.Zero);
if (hr != 0) throw new Win32Exception(hr);
pebAddress = peb32.ToInt64();
IntPtr pp = new IntPtr();
if (!ReadProcessMemory(handle, new IntPtr(pebAddress + processParametersOffset), ref pp, new IntPtr(Marshal.SizeOf(pp)), IntPtr.Zero))
throw new Win32Exception(Marshal.GetLastWin32Error());
UNICODE_STRING_32 us = new UNICODE_STRING_32();
if (!ReadProcessMemory(handle, new IntPtr(pp.ToInt64() + offset), ref us, new IntPtr(Marshal.SizeOf(us)), IntPtr.Zero))
throw new Win32Exception(Marshal.GetLastWin32Error());
if ((us.Buffer == 0) || (us.Length == 0))
return null;
string s = new string('\0', us.Length / 2);
if (!ReadProcessMemory(handle, new IntPtr(us.Buffer), s, new IntPtr(us.Length), IntPtr.Zero))
throw new Win32Exception(Marshal.GetLastWin32Error());
return s;
}
else if (IsWow64Process)//Os : 64Bit, Cur 32, Tar 64
{
PROCESS_BASIC_INFORMATION_WOW64 pbi = new PROCESS_BASIC_INFORMATION_WOW64();
int hr = NtWow64QueryInformationProcess64(handle, (int)PROCESSINFOCLASS.ProcessBasicInformation, ref pbi, Marshal.SizeOf(pbi), IntPtr.Zero);
if (hr != 0) throw new Win32Exception(hr);
pebAddress = pbi.PebBaseAddress;
long pp = 0;
hr = NtWow64ReadVirtualMemory64(handle, pebAddress + processParametersOffset, ref pp, Marshal.SizeOf(pp), IntPtr.Zero);
if (hr != 0)
throw new Win32Exception(hr);
UNICODE_STRING_WOW64 us = new UNICODE_STRING_WOW64();
hr = NtWow64ReadVirtualMemory64(handle, pp + offset, ref us, Marshal.SizeOf(us), IntPtr.Zero);
if (hr != 0)
throw new Win32Exception(hr);
if ((us.Buffer == 0) || (us.Length == 0))
return null;
string s = new string('\0', us.Length / 2);
hr = NtWow64ReadVirtualMemory64(handle, us.Buffer, s, us.Length, IntPtr.Zero);
if (hr != 0)
throw new Win32Exception(hr);
return s;
}
else// Os,Cur,Tar : 64 or 32
{
PROCESS_BASIC_INFORMATION pbi = new PROCESS_BASIC_INFORMATION();
int hr = NtQueryInformationProcess(handle, (int)PROCESSINFOCLASS.ProcessBasicInformation, ref pbi, Marshal.SizeOf(pbi), IntPtr.Zero);
if (hr != 0) throw new Win32Exception(hr);
pebAddress = pbi.PebBaseAddress.ToInt64();
IntPtr pp = new IntPtr();
if (!ReadProcessMemory(handle, new IntPtr(pebAddress + processParametersOffset), ref pp, new IntPtr(Marshal.SizeOf(pp)), IntPtr.Zero))
throw new Win32Exception(Marshal.GetLastWin32Error());
UNICODE_STRING us = new UNICODE_STRING();
if (!ReadProcessMemory(handle, new IntPtr((long)pp + offset), ref us, new IntPtr(Marshal.SizeOf(us)), IntPtr.Zero))
throw new Win32Exception(Marshal.GetLastWin32Error());
if ((us.Buffer == IntPtr.Zero) || (us.Length == 0))
return null;
string s = new string('\0', us.Length / 2);
if (!ReadProcessMemory(handle, us.Buffer, s, new IntPtr(us.Length), IntPtr.Zero))
throw new Win32Exception(Marshal.GetLastWin32Error());
return s;
}
}
finally
{
CloseHandle(handle);
}
}
private const int PROCESS_QUERY_INFORMATION = 0x400;
private const int PROCESS_VM_READ = 0x10;
[StructLayout(LayoutKind.Sequential)]
private struct PROCESS_BASIC_INFORMATION
{
public IntPtr Reserved1;
public IntPtr PebBaseAddress;
public IntPtr Reserved2_0;
public IntPtr Reserved2_1;
public IntPtr UniqueProcessId;
public IntPtr Reserved3;
}
[StructLayout(LayoutKind.Sequential)]
private struct UNICODE_STRING
{
public short Length;
public short MaximumLength;
public IntPtr Buffer;
}
// for 32-bit process in a 64-bit OS only
[StructLayout(LayoutKind.Sequential)]
private struct PROCESS_BASIC_INFORMATION_WOW64
{
public long Reserved1;
public long PebBaseAddress;
public long Reserved2_0;
public long Reserved2_1;
public long UniqueProcessId;
public long Reserved3;
}
// for 32-bit process
[StructLayout(LayoutKind.Sequential)]
private struct UNICODE_STRING_WOW64
{
public short Length;
public short MaximumLength;
public long Buffer;
}
[StructLayout(LayoutKind.Sequential)]
private struct UNICODE_STRING_32
{
public short Length;
public short MaximumLength;
public int Buffer;
}
[DllImport("ntdll.dll")]
private static extern int NtQueryInformationProcess(IntPtr ProcessHandle, int ProcessInformationClass, ref PROCESS_BASIC_INFORMATION ProcessInformation, int ProcessInformationLength, IntPtr ReturnLength);
//ProcessWow64Information, // q: ULONG_PTR
[DllImport("ntdll.dll")]
private static extern int NtQueryInformationProcess(IntPtr ProcessHandle, int ProcessInformationClass, ref IntPtr ProcessInformation, int ProcessInformationLength, IntPtr ReturnLength);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool ReadProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, ref IntPtr lpBuffer, IntPtr dwSize, IntPtr lpNumberOfBytesRead);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool ReadProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, ref UNICODE_STRING lpBuffer, IntPtr dwSize, IntPtr lpNumberOfBytesRead);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool ReadProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, ref UNICODE_STRING_32 lpBuffer, IntPtr dwSize, IntPtr lpNumberOfBytesRead);
//[DllImport("kernel32.dll", SetLastError = true)]
//private static extern bool ReadProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, ref UNICODE_STRING_WOW64 lpBuffer, IntPtr dwSize, IntPtr lpNumberOfBytesRead);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool ReadProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, [MarshalAs(UnmanagedType.LPWStr)] string lpBuffer, IntPtr dwSize, IntPtr lpNumberOfBytesRead);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern IntPtr OpenProcess(int dwDesiredAccess, bool bInheritHandle, int dwProcessId);
[DllImport("kernel32.dll")]
private static extern bool CloseHandle(IntPtr hObject);
// for 32-bit process in a 64-bit OS only
[DllImport("ntdll.dll")]
private static extern int NtWow64QueryInformationProcess64(IntPtr ProcessHandle, int ProcessInformationClass, ref PROCESS_BASIC_INFORMATION_WOW64 ProcessInformation, int ProcessInformationLength, IntPtr ReturnLength);
[DllImport("ntdll.dll")]
private static extern int NtWow64ReadVirtualMemory64(IntPtr hProcess, long lpBaseAddress, ref long lpBuffer, long dwSize, IntPtr lpNumberOfBytesRead);
[DllImport("ntdll.dll")]
private static extern int NtWow64ReadVirtualMemory64(IntPtr hProcess, long lpBaseAddress, ref UNICODE_STRING_WOW64 lpBuffer, long dwSize, IntPtr lpNumberOfBytesRead);
[DllImport("ntdll.dll")]
private static extern int NtWow64ReadVirtualMemory64(IntPtr hProcess, long lpBaseAddress, [MarshalAs(UnmanagedType.LPWStr)] string lpBuffer, long dwSize, IntPtr lpNumberOfBytesRead);
}

C# using SendMessage, problem with WM_COPYDATA

I've been spending a few days (or more) trying to get this to work.
The application at hand is FTPRush, and I know there is a cmd line application called rush_cmdline.exe which uses SendMessage to send requests to FTPRush.
From debugging the rush_cmdline.exe I can see lParam, wParam, Message and hWnd.
My code is as follows (using SendMessage, not SendMessageW):
[DllImport("User32.dll", EntryPoint = "FindWindow")]
public static extern Int32 FindWindow(String lpClassName, String lpWindowName);
[DllImport("USER32.DLL", EntryPoint= "SendMessage")]
public static extern IntPtr SendMessage(int hWnd, int Msg, int wParam, IntPtr lParam);
And I've tried a another specification also:
[DllImport("User32.dll", EntryPoint = "SendMessage")]
public static extern int SendMessage(int hWnd, int Msg, int wParam, ref COPYDATASTRUCT lParam);
The handle (hWnd) is not the problem, as this works:
int ftprush = FindWindow("TfmRush", null);
ShowWindow(ftprush, 8);
Which (I didn't paste the dllimport as it's not important here. Let me know if you wish to see it) brings the window to front. Also, I checked by debugging rush_cmdline.exe. So the handle is the same.
Two attempts which both fail (silently):
public const Int32 WM_COPYDATA = 0x4A;
string msg = "RushApp.FTP.Login('backup','',0); ";
// 1
byte[] array = Encoding.UTF8.GetBytes((string)msg);
int size = Marshal.SizeOf(array[0]) * array.Length + Marshal.SizeOf(array[0]);
IntPtr ptr = Marshal.AllocHGlobal(size);
Marshal.Copy(array, 0, ptr, array.Length);
Marshal.WriteByte(ptr, size - 1, 0);
SendMessage(ftprush, WM_COPYDATA, 0, ptr);
// 2
public struct COPYDATASTRUCT
{
public IntPtr dwData;
public int cbData;
[MarshalAs(UnmanagedType.LPStr)]
public string lpData;
}
COPYDATASTRUCT cds;
cds.dwData = (IntPtr)100;
cds.lpData = msg;
cds.cbData = sarr.Length + 1;
SendMessage(ftprush, WM_COPYDATA, 0, ref cds);
I would expect at least the 2nd solution to work, as it matches up pretty well with this: perl example
Any enlightenment is GREATLY appreciated!
Thanks,
Frank
UPDATE:
string msg = "RushApp.FTP.Login('backup','',0);\0";
var cds = new COPYDATASTRUCT
{
dwData = new IntPtr(3),
cbData = msg.Length + 1,
lpData = msg
};
IntPtr ftprush = FindWindow("TfmRush", null);
SendMessage(ftprush, WM_COPYDATA, IntPtr.Zero, ref cds);

My Definitions have
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = false)]
public static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, ref COPYDATASTRUCT lParam);
public struct COPYDATASTRUCT {
public int cbData;
public IntPtr dwData;
[MarshalAs(UnmanagedType.LPStr)] public string lpData;
}
var cds = new Win32.COPYDATASTRUCT {
dwData = new IntPtr(3),
cbData = str.Length + 1,
lpData = str
};
Win32.SendMessage(ftprush, Win32.WM_COPYDATA, IntPtr.Zero, ref cds);
Of course, make sure that str is null terminated "\0"
Alternatively a definition given by PInvoke.NET is
[DllImport("user32.dll", CharSet = CharSet.Auto)]
static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, StringBuilder lParam);
//If you use '[Out] StringBuilder', initialize the string builder with proper length first.

Between the 2 answers above I cobbled together a working example. Bryce Wagner's class works, so I added a method to use SendMessageTimeout to send the data. it's a static method, so you just call it to send data. This isn't really my work, just gluing together and sharing back.
[StructLayout(LayoutKind.Sequential)]
public struct CopyData: IDisposable {
[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = false)]
static extern IntPtr SendMessageTimeout(IntPtr hWnd, uint Msg, IntPtr wParam, ref CopyData target,
SendMessageTimeoutFlags fuFlags, uint uTimeout, out UIntPtr lpdwResult);
[Flags]
enum SendMessageTimeoutFlags: uint {
SMTO_NORMAL = 0x0,
SMTO_BLOCK = 0x1,
SMTO_ABORTIFHUNG = 0x2,
SMTO_NOTIMEOUTIFNOTHUNG = 0x8
}
const uint WM_COPYDATA = 0x4A;
public IntPtr dwData;
public int cbData;
public IntPtr lpData;
public void Dispose() {
if (lpData != IntPtr.Zero) {
Marshal.FreeCoTaskMem(lpData);
lpData = IntPtr.Zero;
cbData = 0;
}
}
public string AsAnsiString {
get { return Marshal.PtrToStringAnsi(lpData, cbData); }
}
public string AsUnicodeString {
get { return Marshal.PtrToStringUni(lpData); }
}
public static CopyData CreateForString(int dwData, string value, bool Unicode = false) {
var result = new CopyData();
result.dwData = (IntPtr) dwData;
result.lpData = Unicode ? Marshal.StringToCoTaskMemUni(value) : Marshal.StringToCoTaskMemAnsi(value);
result.cbData = value.Length + 1;
return result;
}
public static UIntPtr Send(IntPtr targetHandle, int dwData, string value, uint timeoutMs = 1000, bool Unicode = false) {
var cds = CopyData.CreateForString(dwData, value, Unicode);
UIntPtr result;
SendMessageTimeout(targetHandle, WM_COPYDATA, IntPtr.Zero, ref cds, SendMessageTimeoutFlags.SMTO_NORMAL, timeoutMs, out result);
cds.Dispose();
return result;
}
}
To use it:
CopyData.Send(targetHandle, 1234, "This is a test");
That uses the default 1 second timeout.

The order of arguments in the COPYDATASTRUCT are critically important, and Bob Vale's answer has them in the wrong order. http://msdn.microsoft.com/en-us/library/windows/desktop/ms649010(v=vs.85).aspx It should be in this order:
[StructLayout(LayoutKind.Sequential)]
public struct COPYDATASTRUCT
{
public IntPtr dwData;
public int cbData;
public IntPtr lpData;
}
I haven't gotten the MarshalAs(UnmanagedType.LPStr)] public string lpData to work either. I've only gotten it to work by doing the marshalling myself:
[StructLayout(LayoutKind.Sequential)]
public struct COPYDATASTRUCT : IDisposable
{
public IntPtr dwData;
public int cbData;
public IntPtr lpData;
/// <summary>
/// Only dispose COPYDATASTRUCT if you were the one who allocated it
/// </summary>
public void Dispose()
{
if (lpData != IntPtr.Zero)
{
Marshal.FreeCoTaskMem(lpData);
lpData = IntPtr.Zero;
cbData = 0;
}
}
public string AsAnsiString { get { return Marshal.PtrToStringAnsi(lpData, cbData); } }
public string AsUnicodeString { get { return Marshal.PtrToStringUni(lpData); } }
public static COPYDATASTRUCT CreateForString(int dwData, string value, bool Unicode = false)
{
var result = new COPYDATASTRUCT();
result.dwData = (IntPtr)dwData;
result.lpData = Unicode ? Marshal.StringToCoTaskMemUni(value) : Marshal.StringToCoTaskMemAnsi(value);
result.cbData = value.Length + 1;
return result;
}
}