Develop Reference

Can't read privileges from process access token

I'm trying to get the list of groups and privileges in a process access token and some info about them (name, flags and description).
To do this I'm using the GetTokenInfomation function and the TOKEN_GROUPS_AND_PRIVILEGES structure.
These are the structure definitions:
TOKEN_GROUPS_AND_PRIVILEGES
[StructLayout(LayoutKind.Sequential)]
public struct TOKEN_GROUPS_AND_PRIVILEGES
{
public uint SidCount;
public uint SidLength;
public IntPtr Sids;
public uint RestrictedSidCount;
public uint RestrictedSidLength;
public IntPtr RestrictedSids;
public uint PrivilegeCount;
public uint PrivilegeLength;
public IntPtr Privileges;
public LUID AuthenticationID;
}
LUID_AND_ATTRIBUTES
[StructLayout(LayoutKind.Sequential)]
public struct LUID_AND_ATTRIBUTES
{
public LUID Luid;
public uint Attributes;
}
LUID
[StructLayout(LayoutKind.Sequential)]
public struct LUID
{
public uint LowPart;
public int HighPart;
}
I can read the groups SIDs and get info on them fine but when I try to read the privileges I always get an Access violation.
This is the code that I use to read the privileges:
for (int i = 0; i < GroupsAndPrivilegesInfo.PrivilegeCount; i++)
{
Privilege = (Win32Structures.LUID_AND_ATTRIBUTES)Marshal.PtrToStructure(GroupsAndPrivilegesInfo.Privileges, typeof(Win32Structures.LUID_AND_ATTRIBUTES));
PrivilegeName = GetPrivilegeName(Privilege.Luid) ?? "Non disponibile";
PrivilegeStatus = GetPrivilegeFlags((Win32Enumerations.PrivilegeLUIDAttribute)Privilege.Attributes) ?? "Non disponibile";
PrivilegeDescription = GetPrivilegeDescription(PrivilegeName) ?? "Non disponibile";
Privileges.Add(new TokenPrivilegeInfo(PrivilegeName, PrivilegeStatus, PrivilegeDescription));
GroupsAndPrivilegesInfo.Privileges += Marshal.SizeOf(typeof(Win32Structures.LUID_AND_ATTRIBUTES));
}
The exception occurs when calling the GetPrivilegeName method which uses the function LookupPrivilegeNameW defined as follows:
[DllImport("Advapi32.dll", EntryPoint = "LookupPrivilegeNameW", CharSet = CharSet.Unicode, SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool LookupPrivilegeName(string SystemName, Win32Structures.LUID LUID, StringBuilder PrivilegeName, ref uint NameLength);
I tried different methods to read the data such as:
Manually calculating the offset to the privileges array element from the start of the structure
Declare the privileges field as an array and set a SizeConst to an obviously oversized value
Even those methods threw an Access violation exception.
I don't undestand what is the problem given that I use the same code to read the SIDs and it works normally.

First, The second parameter of LookupPrivilegeNameW is A pointer to a LUID. You need to declare it as a reference type like ref Win32Structures.LUID LUID.
And then the TOKEN_GROUPS_AND_PRIVILEGES.Privileges is an array of the privileges.
Your code does not retrieve all Privileges, but repeatedly reads the first Privilege every time.
Here is the working sample:
namespace ConsoleApp2
{
class Program
{
[StructLayout(LayoutKind.Sequential)]
public struct TOKEN_GROUPS_AND_PRIVILEGES
{
public uint SidCount;
public uint SidLength;
public IntPtr Sids;
public uint RestrictedSidCount;
public uint RestrictedSidLength;
public IntPtr RestrictedSids;
public uint PrivilegeCount;
public uint PrivilegeLength;
public IntPtr Privileges;
public LUID AuthenticationID;
}
[StructLayout(LayoutKind.Sequential)]
public struct LUID_AND_ATTRIBUTES
{
public LUID Luid;
public uint Attributes;
}
[StructLayout(LayoutKind.Sequential)]
public struct LUID
{
public uint LowPart;
public int HighPart;
}
public enum TOKEN_INFORMATION_CLASS
{
TokenUser = 1,
TokenGroups,
TokenPrivileges,
TokenOwner,
TokenPrimaryGroup,
TokenDefaultDacl,
TokenSource,
TokenType,
TokenImpersonationLevel,
TokenStatistics,
TokenRestrictedSids,
TokenSessionId,
TokenGroupsAndPrivileges,
TokenSessionReference,
TokenSandBoxInert,
TokenAuditPolicy,
TokenOrigin
}
[DllImport("Advapi32.dll", EntryPoint = "LookupPrivilegeNameW", CharSet = CharSet.Unicode, SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool LookupPrivilegeName(string SystemName, ref LUID LUID, StringBuilder PrivilegeName, ref uint NameLength);
[DllImport("advapi32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool OpenProcessToken(IntPtr ProcessHandle,
UInt32 DesiredAccess, out IntPtr TokenHandle);
[DllImport("kernel32.dll")]
public static extern IntPtr GetCurrentProcess();
[DllImport("advapi32.dll", SetLastError = true)]
public static extern bool GetTokenInformation(IntPtr TokenHandle,
TOKEN_INFORMATION_CLASS TokenInformationClass,
IntPtr TokenInformation,
Int32 TokenInformationLength,
out Int32 ReturnLength);
public static UInt32 TOKEN_QUERY = 0x0008;
static void Main(string[] args)
{
bool ret = false;
IntPtr token;
ret = OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, out token);
Int32 ReturnLength;
ret = GetTokenInformation(token, TOKEN_INFORMATION_CLASS.TokenGroupsAndPrivileges, IntPtr.Zero, 0, out ReturnLength);
IntPtr pGroupsAndPrivilegesInfo = Marshal.AllocHGlobal(ReturnLength);
ret = GetTokenInformation(token, TOKEN_INFORMATION_CLASS.TokenGroupsAndPrivileges, pGroupsAndPrivilegesInfo, ReturnLength, out ReturnLength);
TOKEN_GROUPS_AND_PRIVILEGES GroupsAndPrivilegesInfo = (TOKEN_GROUPS_AND_PRIVILEGES)Marshal.PtrToStructure(pGroupsAndPrivilegesInfo, typeof(TOKEN_GROUPS_AND_PRIVILEGES));
for (int i = 0; i < GroupsAndPrivilegesInfo.PrivilegeCount; i++)
{
//IntPtr ptr = GroupsAndPrivilegesInfo.Privileges + i * Marshal.SizeOf(typeof(LUID_AND_ATTRIBUTES));
LUID_AND_ATTRIBUTES Privilege = (LUID_AND_ATTRIBUTES)Marshal.PtrToStructure(GroupsAndPrivilegesInfo.Privileges + i * Marshal.SizeOf(typeof(LUID_AND_ATTRIBUTES)), typeof(LUID_AND_ATTRIBUTES));
StringBuilder name = new StringBuilder(50);
uint cchName = 50;
ret = LookupPrivilegeName(null, ref Privilege.Luid, name, ref cchName);
Console.WriteLine(name);
}
Marshal.FreeHGlobal(pGroupsAndPrivilegesInfo);
}
}
}

How to load registry hive for a newly created windows user who have never login?

I created a new windows user using C# and I would like to restrict list of apps to run through setting registry using C#. But the user profile and its registry is not initialized yet, since the user has never login, it will not have registry hive loaded and I cannot make changes.
I have tried Process.start() and set LoadUserProfile=true. I can see that the folder for the user is created under C:\Users\
However, if I get the user's sid and check HKEY_USERS\ , there is no such entry. I learned that when a user login, windows will load the registry hive, and unload when log out. Therefore I need to load the registry hive without user login.
Reference:
Editing registry value for newly created user
Load registry hive from C# fails
Get sid
NTAccount user = new NTAccount(username);
SecurityIdentifier s = (SecurityIdentifier)user.Translate(typeof(SecurityIdentifier));
string sidString = s.ToString();
Load Registry
public class RegistryTest
{
[StructLayout(LayoutKind.Sequential)]
private struct LUID
{
public uint LowPart;
public int HighPart;
}
[StructLayout(LayoutKind.Sequential)]
private struct LUID_AND_ATTRIBUTES
{
public LUID pLuid;
public UInt32 Attributes;
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
private struct TokPriv1Luid
{
public int Count;
public LUID Luid;
public UInt32 Attr;
}
private const Int32 ANYSIZE_ARRAY = 1;
private const UInt32 SE_PRIVILEGE_ENABLED = 0x00000002;
private const UInt32 TOKEN_ADJUST_PRIVILEGES = 0x0020;
private const UInt32 TOKEN_QUERY = 0x0008;
private const uint HKEY_USERS = 0x80000003;
private const string SE_RESTORE_NAME = "SeRestorePrivilege";
private const string SE_BACKUP_NAME = "SeBackupPrivilege";
[DllImport("kernel32.dll")]
static extern IntPtr GetCurrentProcess();
[DllImport("advapi32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool OpenProcessToken(IntPtr ProcessHandle, UInt32 DesiredAccess, out IntPtr TokenHandle);
[DllImport("advapi32.dll", SetLastError = true, CharSet = CharSet.Auto)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool LookupPrivilegeValue(string lpSystemName, string lpName, out LUID lpLuid);
[DllImport("advapi32.dll", ExactSpelling = true, SetLastError = true)]
static extern bool AdjustTokenPrivileges(
IntPtr htok,
bool disableAllPrivileges,
ref TokPriv1Luid newState,
int len,
IntPtr prev,
IntPtr relen);
[DllImport("advapi32.dll", SetLastError = true)]
static extern int RegLoadKey(UInt32 hKey, String lpSubKey, String lpFile);
[DllImport("advapi32.dll", SetLastError = true)]
static extern int RegUnLoadKey(UInt32 hKey, string lpSubKey);
private IntPtr _myToken;
private TokPriv1Luid _tokenPrivileges = new TokPriv1Luid();
private TokPriv1Luid _tokenPrivileges2 = new TokPriv1Luid();
private LUID _restoreLuid;
private LUID _backupLuid;
public RegistryTest(string sid)
{
if (!OpenProcessToken(GetCurrentProcess(), TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY, out _myToken))
Console.WriteLine("OpenProcess Error");
if (!LookupPrivilegeValue(null, SE_RESTORE_NAME, out _restoreLuid))
Console.WriteLine("LookupPrivilegeValue Error");
if (!LookupPrivilegeValue(null, SE_BACKUP_NAME, out _backupLuid))
Console.WriteLine("LookupPrivilegeValue Error");
_tokenPrivileges.Attr = SE_PRIVILEGE_ENABLED;
_tokenPrivileges.Luid = _restoreLuid;
_tokenPrivileges.Count = 1;
_tokenPrivileges2.Attr = SE_PRIVILEGE_ENABLED;
_tokenPrivileges2.Luid = _backupLuid;
_tokenPrivileges2.Count = 1;
if (!AdjustTokenPrivileges(_myToken, false, ref _tokenPrivileges, 0, IntPtr.Zero, IntPtr.Zero))
Console.WriteLine("AdjustTokenPrivileges Error: " + Marshal.GetLastWin32Error());
if (!AdjustTokenPrivileges(_myToken, false, ref _tokenPrivileges2, 0, IntPtr.Zero, IntPtr.Zero))
Console.WriteLine("AdjustTokenPrivileges Error: " + Marshal.GetLastWin32Error());
// --> RegLoadKey fails with return value 32<--
int retVal = RegLoadKey(HKEY_USERS, sid, #"C:\Users\Default\NTUSER.DAT");
if (retVal != 0)
Console.WriteLine("RegLoadKey Error:" + retVal);
}
}
The RegLoadKey API should return 0 but I got 32

I have find a way to do it, I load default registry hive in C:\Users\Default. After I change it to C:\Users\[username]\NTUSER.DAT and then the registry hive is loaded.

PowerShell + C# Elevate-Privileges Function Explained

Can anyone explain what this function written in PowerShell/C# is doing or why it's required? I use it take ownership of things programatically but would like to know what the C# code is doing.
function Elevate-Privileges {
param($Privilege)
$Definition = #"
using System;
using System.Runtime.InteropServices;
public class AdjPriv {
[DllImport("advapi32.dll", ExactSpelling = true, SetLastError = true)]
internal static extern bool AdjustTokenPrivileges(IntPtr htok, bool disall, ref TokPriv1Luid newst, int len, IntPtr prev, IntPtr rele);
[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_ENABLED = 0x00000002;
internal const int TOKEN_QUERY = 0x00000008;
internal const int TOKEN_ADJUST_PRIVILEGES = 0x00000020;
public static bool EnablePrivilege(long processHandle, string privilege) {
bool retVal;
TokPriv1Luid tp;
IntPtr hproc = new IntPtr(processHandle);
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;
}
}
"#
$ProcessHandle = (Get-Process -id $pid).Handle
$type = Add-Type $definition -PassThru
$type[0]::EnablePrivilege($processHandle, $Privilege)
}

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;
}
}

Run a process from a windows service as the current user

I currently have a windows service that is running under the System Account. My problem is that i need to start certain processes from within the service as the current logged on user. I have all the code etc to get the current logged on user / Active session.
My problem is that i need spawn a process as the logged on user but will not know the user credentials etc.
The service is .net compiled service and i expect that i need to use some Pinvoke methods to get a handle of one of the current users process in order to duplicate it and lunch as process with the handle.
Unfortunately i cannot find any good documentation / solution on how to implement it?
If someone is able to give me some guidance / example i would highly appreciate it.
* Updated *
I think i have explained this incorrectly and need to reajust according to what i actually require. I do not necessarily want to launch a new process, i just want to impersonate the logged on user. I have been so wrapped up at looking at CreateProcess etc i have lead myself down a path of create a new process as the current logged in user (which is not particularly what i want to do).
In turn i just want to run some code under the current user context (Impersonate the current Logged on user)?

One option is to have background application that automatically starts when user logs on and listens to commands from your service through WCF, or thrift, or by just monitoring some file and reading command from there.
Another option is to do what you originally asked for - launch using windows API. But the code is quite scary. Here is a sample, that you can use. It will execute any command line under currently active user session, with CreateProcessInConsoleSession method:
internal class ApplicationLauncher
{
public enum TOKEN_INFORMATION_CLASS
{
TokenUser = 1,
TokenGroups,
TokenPrivileges,
TokenOwner,
TokenPrimaryGroup,
TokenDefaultDacl,
TokenSource,
TokenType,
TokenImpersonationLevel,
TokenStatistics,
TokenRestrictedSids,
TokenSessionId,
TokenGroupsAndPrivileges,
TokenSessionReference,
TokenSandBoxInert,
TokenAuditPolicy,
TokenOrigin,
MaxTokenInfoClass // MaxTokenInfoClass should always be the last enum
}
public const int READ_CONTROL = 0x00020000;
public const int STANDARD_RIGHTS_REQUIRED = 0x000F0000;
public const int STANDARD_RIGHTS_READ = READ_CONTROL;
public const int STANDARD_RIGHTS_WRITE = READ_CONTROL;
public const int STANDARD_RIGHTS_EXECUTE = READ_CONTROL;
public const int STANDARD_RIGHTS_ALL = 0x001F0000;
public const int SPECIFIC_RIGHTS_ALL = 0x0000FFFF;
public const int TOKEN_ASSIGN_PRIMARY = 0x0001;
public const int TOKEN_DUPLICATE = 0x0002;
public const int TOKEN_IMPERSONATE = 0x0004;
public const int TOKEN_QUERY = 0x0008;
public const int TOKEN_QUERY_SOURCE = 0x0010;
public const int TOKEN_ADJUST_PRIVILEGES = 0x0020;
public const int TOKEN_ADJUST_GROUPS = 0x0040;
public const int TOKEN_ADJUST_DEFAULT = 0x0080;
public const int TOKEN_ADJUST_SESSIONID = 0x0100;
public const int TOKEN_ALL_ACCESS_P = (STANDARD_RIGHTS_REQUIRED |
TOKEN_ASSIGN_PRIMARY |
TOKEN_DUPLICATE |
TOKEN_IMPERSONATE |
TOKEN_QUERY |
TOKEN_QUERY_SOURCE |
TOKEN_ADJUST_PRIVILEGES |
TOKEN_ADJUST_GROUPS |
TOKEN_ADJUST_DEFAULT);
public const int TOKEN_ALL_ACCESS = TOKEN_ALL_ACCESS_P | TOKEN_ADJUST_SESSIONID;
public const int TOKEN_READ = STANDARD_RIGHTS_READ | TOKEN_QUERY;
public const int TOKEN_WRITE = STANDARD_RIGHTS_WRITE |
TOKEN_ADJUST_PRIVILEGES |
TOKEN_ADJUST_GROUPS |
TOKEN_ADJUST_DEFAULT;
public const int TOKEN_EXECUTE = STANDARD_RIGHTS_EXECUTE;
public const uint MAXIMUM_ALLOWED = 0x2000000;
public const int CREATE_NEW_PROCESS_GROUP = 0x00000200;
public const int CREATE_UNICODE_ENVIRONMENT = 0x00000400;
public const int IDLE_PRIORITY_CLASS = 0x40;
public const int NORMAL_PRIORITY_CLASS = 0x20;
public const int HIGH_PRIORITY_CLASS = 0x80;
public const int REALTIME_PRIORITY_CLASS = 0x100;
public const int CREATE_NEW_CONSOLE = 0x00000010;
public const string SE_DEBUG_NAME = "SeDebugPrivilege";
public const string SE_RESTORE_NAME = "SeRestorePrivilege";
public const string SE_BACKUP_NAME = "SeBackupPrivilege";
public const int SE_PRIVILEGE_ENABLED = 0x0002;
public const int ERROR_NOT_ALL_ASSIGNED = 1300;
private const uint TH32CS_SNAPPROCESS = 0x00000002;
public static int INVALID_HANDLE_VALUE = -1;
[DllImport("advapi32.dll", SetLastError = true)]
public static extern bool LookupPrivilegeValue(IntPtr lpSystemName, string lpname,
[MarshalAs(UnmanagedType.Struct)] ref LUID lpLuid);
[DllImport("advapi32.dll", EntryPoint = "CreateProcessAsUser", SetLastError = true, CharSet = CharSet.Ansi,
CallingConvention = CallingConvention.StdCall)]
public static extern bool CreateProcessAsUser(IntPtr hToken, String lpApplicationName, String lpCommandLine,
ref SECURITY_ATTRIBUTES lpProcessAttributes,
ref SECURITY_ATTRIBUTES lpThreadAttributes, bool bInheritHandle, int dwCreationFlags, IntPtr lpEnvironment,
String lpCurrentDirectory, ref STARTUPINFO lpStartupInfo, out PROCESS_INFORMATION lpProcessInformation);
[DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
public static extern bool DuplicateToken(IntPtr ExistingTokenHandle,
int SECURITY_IMPERSONATION_LEVEL, ref IntPtr DuplicateTokenHandle);
[DllImport("advapi32.dll", EntryPoint = "DuplicateTokenEx")]
public static extern bool DuplicateTokenEx(IntPtr ExistingTokenHandle, uint dwDesiredAccess,
ref SECURITY_ATTRIBUTES lpThreadAttributes, int TokenType,
int ImpersonationLevel, ref IntPtr DuplicateTokenHandle);
[DllImport("advapi32.dll", SetLastError = true)]
public static extern bool AdjustTokenPrivileges(IntPtr TokenHandle, bool DisableAllPrivileges,
ref TOKEN_PRIVILEGES NewState, int BufferLength, IntPtr PreviousState, IntPtr ReturnLength);
[DllImport("advapi32.dll", SetLastError = true)]
public static extern bool SetTokenInformation(IntPtr TokenHandle, TOKEN_INFORMATION_CLASS TokenInformationClass,
ref uint TokenInformation, uint TokenInformationLength);
[DllImport("userenv.dll", SetLastError = true)]
public static extern bool CreateEnvironmentBlock(ref IntPtr lpEnvironment, IntPtr hToken, bool bInherit);
public static bool CreateProcessInConsoleSession(String CommandLine, bool bElevate)
{
PROCESS_INFORMATION pi;
bool bResult = false;
uint dwSessionId, winlogonPid = 0;
IntPtr hUserToken = IntPtr.Zero, hUserTokenDup = IntPtr.Zero, hPToken = IntPtr.Zero, hProcess = IntPtr.Zero;
Debug.Print("CreateProcessInConsoleSession");
// Log the client on to the local computer.
dwSessionId = WTSGetActiveConsoleSessionId();
// Find the winlogon process
var procEntry = new PROCESSENTRY32();
uint hSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
if (hSnap == INVALID_HANDLE_VALUE)
{
return false;
}
procEntry.dwSize = (uint) Marshal.SizeOf(procEntry); //sizeof(PROCESSENTRY32);
if (Process32First(hSnap, ref procEntry) == 0)
{
return false;
}
String strCmp = "explorer.exe";
do
{
if (strCmp.IndexOf(procEntry.szExeFile) == 0)
{
// We found a winlogon process...make sure it's running in the console session
uint winlogonSessId = 0;
if (ProcessIdToSessionId(procEntry.th32ProcessID, ref winlogonSessId) &&
winlogonSessId == dwSessionId)
{
winlogonPid = procEntry.th32ProcessID;
break;
}
}
}
while (Process32Next(hSnap, ref procEntry) != 0);
//Get the user token used by DuplicateTokenEx
WTSQueryUserToken(dwSessionId, ref hUserToken);
var si = new STARTUPINFO();
si.cb = Marshal.SizeOf(si);
si.lpDesktop = "winsta0\\default";
var tp = new TOKEN_PRIVILEGES();
var luid = new LUID();
hProcess = OpenProcess(MAXIMUM_ALLOWED, false, winlogonPid);
if (
!OpenProcessToken(hProcess,
TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY | TOKEN_DUPLICATE | TOKEN_ASSIGN_PRIMARY
| TOKEN_ADJUST_SESSIONID | TOKEN_READ | TOKEN_WRITE, ref hPToken))
{
Debug.Print(String.Format("CreateProcessInConsoleSession OpenProcessToken error: {0}",
Marshal.GetLastWin32Error()));
}
if (!LookupPrivilegeValue(IntPtr.Zero, SE_DEBUG_NAME, ref luid))
{
Debug.Print(String.Format("CreateProcessInConsoleSession LookupPrivilegeValue error: {0}",
Marshal.GetLastWin32Error()));
}
var sa = new SECURITY_ATTRIBUTES();
sa.Length = Marshal.SizeOf(sa);
if (!DuplicateTokenEx(hPToken, MAXIMUM_ALLOWED, ref sa,
(int) SECURITY_IMPERSONATION_LEVEL.SecurityIdentification, (int) TOKEN_TYPE.TokenPrimary,
ref hUserTokenDup))
{
Debug.Print(
String.Format(
"CreateProcessInConsoleSession DuplicateTokenEx error: {0} Token does not have the privilege.",
Marshal.GetLastWin32Error()));
CloseHandle(hProcess);
CloseHandle(hUserToken);
CloseHandle(hPToken);
return false;
}
if (bElevate)
{
//tp.Privileges[0].Luid = luid;
//tp.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;
tp.PrivilegeCount = 1;
tp.Privileges = new int[3];
tp.Privileges[2] = SE_PRIVILEGE_ENABLED;
tp.Privileges[1] = luid.HighPart;
tp.Privileges[0] = luid.LowPart;
//Adjust Token privilege
if (
!SetTokenInformation(hUserTokenDup, TOKEN_INFORMATION_CLASS.TokenSessionId, ref dwSessionId,
(uint) IntPtr.Size))
{
Debug.Print(
String.Format(
"CreateProcessInConsoleSession SetTokenInformation error: {0} Token does not have the privilege.",
Marshal.GetLastWin32Error()));
//CloseHandle(hProcess);
//CloseHandle(hUserToken);
//CloseHandle(hPToken);
//CloseHandle(hUserTokenDup);
//return false;
}
if (
!AdjustTokenPrivileges(hUserTokenDup, false, ref tp, Marshal.SizeOf(tp), /*(PTOKEN_PRIVILEGES)*/
IntPtr.Zero, IntPtr.Zero))
{
int nErr = Marshal.GetLastWin32Error();
if (nErr == ERROR_NOT_ALL_ASSIGNED)
{
Debug.Print(
String.Format(
"CreateProcessInConsoleSession AdjustTokenPrivileges error: {0} Token does not have the privilege.",
nErr));
}
else
{
Debug.Print(String.Format("CreateProcessInConsoleSession AdjustTokenPrivileges error: {0}", nErr));
}
}
}
uint dwCreationFlags = NORMAL_PRIORITY_CLASS | CREATE_NEW_CONSOLE;
IntPtr pEnv = IntPtr.Zero;
if (CreateEnvironmentBlock(ref pEnv, hUserTokenDup, true))
{
dwCreationFlags |= CREATE_UNICODE_ENVIRONMENT;
}
else
{
pEnv = IntPtr.Zero;
}
// Launch the process in the client's logon session.
bResult = CreateProcessAsUser(hUserTokenDup, // client's access token
null, // file to execute
CommandLine, // command line
ref sa, // pointer to process SECURITY_ATTRIBUTES
ref sa, // pointer to thread SECURITY_ATTRIBUTES
false, // handles are not inheritable
(int) dwCreationFlags, // creation flags
pEnv, // pointer to new environment block
null, // name of current directory
ref si, // pointer to STARTUPINFO structure
out pi // receives information about new process
);
// End impersonation of client.
//GetLastError should be 0
int iResultOfCreateProcessAsUser = Marshal.GetLastWin32Error();
//Close handles task
CloseHandle(hProcess);
CloseHandle(hUserToken);
CloseHandle(hUserTokenDup);
CloseHandle(hPToken);
return (iResultOfCreateProcessAsUser == 0) ? true : false;
}
[DllImport("kernel32.dll")]
private static extern int Process32First(uint hSnapshot, ref PROCESSENTRY32 lppe);
[DllImport("kernel32.dll")]
private static extern int Process32Next(uint hSnapshot, ref PROCESSENTRY32 lppe);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern uint CreateToolhelp32Snapshot(uint dwFlags, uint th32ProcessID);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool CloseHandle(IntPtr hSnapshot);
[DllImport("kernel32.dll")]
private static extern uint WTSGetActiveConsoleSessionId();
[DllImport("Wtsapi32.dll")]
private static extern uint WTSQueryUserToken(uint SessionId, ref IntPtr phToken);
[DllImport("kernel32.dll")]
private static extern bool ProcessIdToSessionId(uint dwProcessId, ref uint pSessionId);
[DllImport("kernel32.dll")]
private static extern IntPtr OpenProcess(uint dwDesiredAccess, bool bInheritHandle, uint dwProcessId);
[DllImport("advapi32", SetLastError = true)]
[SuppressUnmanagedCodeSecurity]
private static extern bool OpenProcessToken(IntPtr ProcessHandle, // handle to process
int DesiredAccess, // desired access to process
ref IntPtr TokenHandle);
#region Nested type: LUID
[StructLayout(LayoutKind.Sequential)]
internal struct LUID
{
public int LowPart;
public int HighPart;
}
#endregion
//end struct
#region Nested type: LUID_AND_ATRIBUTES
[StructLayout(LayoutKind.Sequential)]
internal struct LUID_AND_ATRIBUTES
{
public LUID Luid;
public int Attributes;
}
#endregion
#region Nested type: PROCESSENTRY32
[StructLayout(LayoutKind.Sequential)]
private struct PROCESSENTRY32
{
public uint dwSize;
public readonly uint cntUsage;
public readonly uint th32ProcessID;
public readonly IntPtr th32DefaultHeapID;
public readonly uint th32ModuleID;
public readonly uint cntThreads;
public readonly uint th32ParentProcessID;
public readonly int pcPriClassBase;
public readonly uint dwFlags;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
public readonly string szExeFile;
}
#endregion
#region Nested type: PROCESS_INFORMATION
[StructLayout(LayoutKind.Sequential)]
public struct PROCESS_INFORMATION
{
public IntPtr hProcess;
public IntPtr hThread;
public uint dwProcessId;
public uint dwThreadId;
}
#endregion
#region Nested type: SECURITY_ATTRIBUTES
[StructLayout(LayoutKind.Sequential)]
public struct SECURITY_ATTRIBUTES
{
public int Length;
public IntPtr lpSecurityDescriptor;
public bool bInheritHandle;
}
#endregion
#region Nested type: SECURITY_IMPERSONATION_LEVEL
private enum SECURITY_IMPERSONATION_LEVEL
{
SecurityAnonymous = 0,
SecurityIdentification = 1,
SecurityImpersonation = 2,
SecurityDelegation = 3,
}
#endregion
#region Nested type: STARTUPINFO
[StructLayout(LayoutKind.Sequential)]
public struct STARTUPINFO
{
public int 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;
}
#endregion
#region Nested type: TOKEN_PRIVILEGES
[StructLayout(LayoutKind.Sequential)]
internal struct TOKEN_PRIVILEGES
{
internal int PrivilegeCount;
//LUID_AND_ATRIBUTES
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
internal int[] Privileges;
}
#endregion
#region Nested type: TOKEN_TYPE
private enum TOKEN_TYPE
{
TokenPrimary = 1,
TokenImpersonation = 2
}
#endregion
// handle to open access token
}

As is so common with these types of questions about Windows services, you're operating in the mindset of a single-user operating system. The whole reason you decided to write your app as a service was because you were running into conflicts between your mental model of a single-user OS and the reality of a multi-user OS. Unfortunately, a service didn't solve all of your problems and now you're trying to figure out how to accomplish step two in the ultimately-doomed hacked design.
The fact is, you cannot be guaranteed that there is a "logged on user". If no one has logged on to the workstation, there will be no one logged on, yet your service will still be running.
Even if you somehow got past this by ensuring that someone will always be logged on (impossible), then you would run into the situation where multiple users are logged on. Then which one should your service start the process as? Should it just pick one of them randomly?
And is it necessary in your case to distinguish between users logged on locally to the console and those who are logged on remotely? Remember that remote users won't have a local console.
If you could somehow get past all of these hurdles (unfortunately, probably by burying your head in the sand and continuing to pretend that Windows is a single-user OS), you could make use of the WTSGetActiveConsoleSessionId function to obtain the current session ID, the WTSQueryUserToken function to obtain the user token corresponding to that session ID, and then finally the CreateProcessAsUser function to launch your process in the context of that user. If there is one. And they have the appropriate privileges. And the physical console is not attached to a dummy session. And you're not running a server SKU that allows multiple active console sessions. And…
If you could decide on a particular user whose account you wish to use to start the auxiliary process, you could log on that user, manipulate their user token, execute the process, and finally close the process and log out the user. The CreateProcessWithLogonUser function wraps up a lot of this drudgery for you, making the code a lot more svelte. But appearances can be deceiving, and this still has some massive security implications that you probably do not completely understand if you're asking this question in the first place. And you really cannot afford to not understand security risks like this.
Besides, users that are logged in with LogonUser (which is done for you automatically when you use the CreateProcessWithLogonUser function) lack a window station and desktop on which they can launch interactive processes. So if the process you wish to launch in the context of that user will show any kind of UI, you're out of luck. Windows will kill your app as soon as it tries to access a desktop for which it lacks the requisite permissions. There is no way, from a Windows service, to obtain the handle of a desktop that will be useful to you (which goes a long way towards explaining the general rule you probably already know, that services cannot display any type of UI).