Running programs using RtlCreateUserProcess only works occasionally - c++

Question

Disclaimer: This questions seems to get downvoted because I should use the normal Win32 API (CreateProcess, ShellExecute). I know about these APIs and I'm aware that RtlCreateUserProcess is not supposed to be called directly. However, the native API is a very relevant topic regarding security, that's why I am researching it.
I'm trying to run programs on Windows using the function RtlCreateUserProcess, exported from ntdll.dll. My code works to run calc.exe, however, after trying to run notepad.exe, I receive an error message that reads The ordinal 345 could not be located in dynamic link library "C:\Windows\SysWOW64\notepad.exe". When trying to run other programs it displays various similar messages, always related to some ordinals or DLLs missing.
My example code looks like this:
#include <windows.h>
#include <iostream>
#include <winternl.h>
typedef struct _SECTION_IMAGE_INFORMATION {
PVOID EntryPoint;
ULONG StackZeroBits;
ULONG StackReserved;
ULONG StackCommit;
ULONG ImageSubsystem;
WORD SubSystemVersionLow;
WORD SubSystemVersionHigh;
ULONG Unknown1;
ULONG ImageCharacteristics;
ULONG ImageMachineType;
ULONG Unknown2[3];
} SECTION_IMAGE_INFORMATION, * PSECTION_IMAGE_INFORMATION;
typedef struct _RTL_USER_PROCESS_INFORMATION {
ULONG Size;
HANDLE ProcessHandle;
HANDLE ThreadHandle;
CLIENT_ID ClientId;
SECTION_IMAGE_INFORMATION ImageInformation;
} RTL_USER_PROCESS_INFORMATION, * PRTL_USER_PROCESS_INFORMATION;
typedef VOID(NTAPI* Func1)(PUNICODE_STRING DestinationString, __drv_aliasesMem PCWSTR SourceString);
typedef NTSTATUS(NTAPI* Func2)(OUT PRTL_USER_PROCESS_PARAMETERS* pProcessParameters, IN PUNICODE_STRING ImagePathName, IN PUNICODE_STRING DllPath OPTIONAL, IN PUNICODE_STRING CurrentDirectory OPTIONAL, IN PUNICODE_STRING CommandLine OPTIONAL, IN PVOID Environment OPTIONAL, IN PUNICODE_STRING WindowTitle OPTIONAL, IN PUNICODE_STRING DesktopInfo OPTIONAL, IN PUNICODE_STRING ShellInfo OPTIONAL, IN PUNICODE_STRING RuntimeData OPTIONAL);
typedef NTSTATUS(NTAPI* Func3)(PUNICODE_STRING NtImagePathName, ULONG Attributes, PRTL_USER_PROCESS_PARAMETERS ProcessParameters, PSECURITY_DESCRIPTOR ProcessSecurityDescriptor, PSECURITY_DESCRIPTOR ThreadSecurityDescriptor, HANDLE ParentProcess, BOOLEAN InheritHandles, HANDLE DebugPort, HANDLE ExceptionPort, PRTL_USER_PROCESS_INFORMATION ProcessInformation);
int main()
{
UNICODE_STRING str;
PRTL_USER_PROCESS_PARAMETERS processparameters;
RTL_USER_PROCESS_INFORMATION processinformation = { 0 };
Func1 RtlInitUnicodeString = (Func1)GetProcAddress(GetModuleHandleW(L"ntdll.dll"), "RtlInitUnicodeString");
Func2 RtlCreateProcessParameters = (Func2)GetProcAddress(GetModuleHandleW(L"ntdll.dll"), "RtlCreateProcessParameters");
Func3 RtlCreateUserProcess = (Func3)GetProcAddress(GetModuleHandleW(L"ntdll.dll"), "RtlCreateUserProcess");
RtlInitUnicodeString(&str, L"\\??\\C:\\Windows\\SysWOW64\\notepad.exe"); //Starting calc.exe works, notepad.exe does not.
RtlCreateProcessParameters(&processparameters, &str, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL);
NTSTATUS works = RtlCreateUserProcess(&str, OBJ_CASE_INSENSITIVE, processparameters, NULL, NULL, NULL, FALSE, NULL, NULL, &processinformation);
if (NT_SUCCESS(works)) {
ResumeThread(processinformation.ThreadHandle);
//Started application crashes at this point + the error message gets shown
}
else {
std::cout << "Failed" << std::endl;
}
return 0;
}
Unfortunately, there is not much information available about using this function, so I would appreciate any answers on how to use this function correctly.

Answer 1

CreateProcess after create new process do much more job, in particular it create activation context for new process based on exe manifest (BasepConstructSxsCreateProcessMessage + CsrClientCallServer) as result new process have initial activation context, stored in PEB (SystemDefaultActivationContextData and ActivationContextData) but in process created with pure call to RtlCreateUserProcess this fields is empty (0). as result your process loaded ComCtl32.dll from system32 (version 5.82 ) and notepad with activation context - 6+ version.
The ordinal 345 could not be located in dynamic link library
really in ComCtl32.DLL pre 6 version (5.82). 345 - this is TaskDialogIndirect api which exist only in ComCtl32.DLL version 6+. but your process load 5.82.. - calling TaskDialogIndirect loader says ordinal 345 not found
so CreateProcess not a thin shell over RtlCreateUserProcess or NtCreateUserProcess, but big and complex api. at it functional very hard if possible at all implement direct