VC IAI HOOK demo

#include <stdio.h>#include <Windows.h>#include <Dbghelp.h>BOOL ModifyImportTable(IMAGE_IMPORT_DESCRIPTOR* iid, void* target,void* replacement){IMAGE_THUNK_DATA* itd = (IMAGE_THUNK_DATA*)(((char*)GetModuleHandle(NULL)) + iid->FirstThunk);while (itd->u1.Function){if (((void*)itd->u1.Function) == target){// Temporary change access to memory area to READWRITEMEMORY_BASIC_INFORMATION mbi;VirtualQuery(itd, &mbi, sizeof(MEMORY_BASIC_INFORMATION));VirtualProtect(mbi.BaseAddress, mbi.RegionSize, PAGE_READWRITE, &mbi.Protect);// Replace entry!!*((void**)itd) = replacement;// Restore memory permissionsVirtualProtect(mbi.BaseAddress, mbi.RegionSize, mbi.Protect, &mbi.Protect);return TRUE;}itd += 1;}return FALSE;}BOOL InstallHook(LPCSTR module, LPCSTR function, void* hook, void** original){HMODULE process = GetModuleHandle(NULL);// Save original address to function*original = (void*)GetProcAddress(GetModuleHandleA(module), function);ULONG entrySize;IMAGE_IMPORT_DESCRIPTOR* iid = (IMAGE_IMPORT_DESCRIPTOR*)ImageDirectoryEntryToData(process, 1, IMAGE_DIRECTORY_ENTRY_IMPORT, &entrySize);// Search for modulewhile (iid->Name){const char* name = ((char*)process) + iid->Name;if (stricmp(name, module) == 0){return ModifyImportTable(iid, *original, hook);}iid += 1;}return FALSE;}int (__stdcall *RealMessageBoxA)(HWND, LPCSTR, LPCSTR, UINT);int __stdcall HookedMessageBoxA(HWND hWnd, LPCSTR lpText, LPCSTR lpCaption, UINT uType){printf("HookedMessageBoxA Program is trying to display a message box with title '%s' and text '%s'.\n\nAllow (y/n)? ",lpCaption,lpText);char choice;scanf_s("%c", &choice);if (choice == 'y'){return RealMessageBoxA(hWnd, lpText, lpCaption, uType);}else{printf("\nSupressing message...\n");return 0;}}int main(){if (InstallHook("User32.dll", "MessageBoxA", (void*)HookedMessageBoxA, (void**)(&RealMessageBoxA))){printf("Hook installed!\n\n");MessageBoxA(NULL, "Let me out!", "I'm trapped!", 0);}else{printf("Failed to install hook!\n");}return 0;}