1 #include <Windows.h>
 2 #include <cstdio>
 3 
 4 BOOL WINAPI DllMain(HINSTANCE, DWORD fdwReason, LPVOID)
 5 {
 6     if (fdwReason == DLL_PROCESS_ATTACH)
 7     {
 8         HANDLE hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE);
 9         DWORD dwOutputMode;
10         if (!GetConsoleMode(hStdOutput, &dwOutputMode))
11         {
12             puts("GetConsoleMode() fail.");
13         }
14         dwOutputMode |= ENABLE_VIRTUAL_TERMINAL_PROCESSING;
15         if (!SetConsoleMode(hStdOutput, dwOutputMode))
16         {
17             puts("SetConsoleMode() fail.");
18         }
19         puts("\x1b[31mHello World!\x1b[0m");
20     }
21     return TRUE;
22 }

  1 #include <Windows.h>
  2 #include <TlHelp32.h>
  3 #include <cstdio>
  4 #include <cstring>
  5 #include <process.h>
  6 
  7 DWORD GetParentProcessId(DWORD dwProcessID)
  8 {
  9     HANDLE hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
 10     if (!hProcessSnap)
 11     {
 12         puts("CreateToolhelp32Snapshot() fail.");
 13         exit(1);
 14     }
 15     PROCESSENTRY32 pe = { 0 };
 16     pe.dwSize = sizeof(PROCESSENTRY32);
 17     if (!Process32First(hProcessSnap, &pe))
 18     {
 19         puts("Process32First() fail.");
 20         exit(1);
 21     }
 22     DWORD dwParentProcessID = 0;
 23     do
 24     {
 25         if (pe.th32ProcessID == dwProcessID)
 26         {
 27             dwParentProcessID = pe.th32ParentProcessID;
 28         }
 29     } while (Process32Next(hProcessSnap, &pe));
 30     CloseHandle(hProcessSnap);
 31     return dwParentProcessID;
 32 }
 33 
 34 PTHREAD_START_ROUTINE pLoadLibrary;
 35 PTHREAD_START_ROUTINE pFreeLibrary;
 36 
 37 void LoadLibraryRemote(HANDLE hProcess, PCWSTR wcsDllName)
 38 {
 39     SIZE_T nSize = (wcslen(wcsDllName) + 1) * sizeof(WCHAR);
 40     PVOID wcsDllNameRemote = VirtualAllocEx(hProcess, NULL, nSize, MEM_COMMIT, PAGE_READWRITE);
 41     if (!wcsDllNameRemote)
 42     {
 43         puts("VirtualAllocEx() fail.");
 44         exit(1);
 45     }
 46     if (!WriteProcessMemory(hProcess, wcsDllNameRemote, wcsDllName, nSize, NULL))
 47     {
 48         puts("WriteProcessMemory() fail.");
 49         exit(1);
 50     }
 51     HANDLE hThread = CreateRemoteThread(hProcess, NULL, NULL, pLoadLibrary, wcsDllNameRemote, NULL, NULL);
 52     if (!hThread)
 53     {
 54         puts("CreateRemoteThread() fail.");
 55     }
 56     WaitForSingleObject(hThread, INFINITE);
 57     VirtualFreeEx(hProcess, wcsDllNameRemote, 0, MEM_RELEASE);
 58     CloseHandle(hThread);
 59 }
 60 
 61 void FreeLibraryRemote(HANDLE hProcess, PCWSTR wcsDllName)
 62 {
 63     DWORD dwProcessID = GetProcessId(hProcess);
 64     HANDLE hModuleSnap = CreateToolhelp32Snapshot(TH32CS_SNAPMODULE, dwProcessID);
 65     if (!hModuleSnap)
 66     {
 67         puts("CreateToolhelp32Snapshot() fail.");
 68         exit(1);
 69     }
 70     MODULEENTRY32 me = { 0 };
 71     me.dwSize = sizeof(MODULEENTRY32);
 72     if (!Module32First(hModuleSnap, &me))
 73     {
 74         puts("Module32First() fail.");
 75         exit(1);
 76     }
 77     PVOID hMod = NULL;
 78     do
 79     {
 80         if (!_wcsicmp(me.szModule, wcsDllName))
 81         {
 82             hMod = me.hModule;
 83             break;
 84         }
 85     } while (Module32Next(hModuleSnap, &me));
 86     if (!hMod)
 87     {
 88         puts("Assertion fail. Module not found.");
 89         exit(1);
 90     }
 91     HANDLE hThread = CreateRemoteThread(hProcess, NULL, NULL, pFreeLibrary, hMod, NULL, NULL);
 92     if (!hThread)
 93     {
 94         puts("CreateRemoteThread() fail.");
 95         exit(1);
 96     }
 97     WaitForSingleObject(hThread, INFINITE);
 98     CloseHandle(hModuleSnap);
 99     CloseHandle(hThread);
100 }
101 
102 int main()
103 {
104     HMODULE hMod = GetModuleHandle(L"kernel32");
105     if (!hMod)
106     {
107         puts("GetModuleHandle() fail.");
108         exit(1);
109     }
110     pLoadLibrary = (PTHREAD_START_ROUTINE)GetProcAddress(hMod, "LoadLibraryW");
111     if (!pLoadLibrary)
112     {
113         puts("GetProcAddress() fail.");
114         exit(1);
115     }
116     pFreeLibrary = (PTHREAD_START_ROUTINE)GetProcAddress(hMod, "FreeLibrary");
117     if (!pLoadLibrary)
118     {
119         puts("GetProcAddress() fail.");
120         exit(1);
121     }
122     DWORD dwCurrentProcessID = GetCurrentProcessId();
123     DWORD dwParentProcessID = GetParentProcessId(dwCurrentProcessID);
124     if (dwParentProcessID == 0)
125     {
126         puts("Assertion fail. Parent process not exist.");
127         exit(1);
128     }
129     HANDLE hProcess = OpenProcess(PROCESS_ALL_ACCESS, FALSE, dwParentProcessID);
130     if (!hProcess)
131     {
132         puts("OpenProcess() fail.");
133         exit(1);
134     }
135     WCHAR wcsImageName[256];
136     DWORD dwSize;
137     if (!QueryFullProcessImageName(hProcess, 0, wcsImageName, &dwSize))
138     {
139         puts("QueryFullProcessImageName() fail.");
140         exit(1);
141     }
142     if (!wcsstr(wcsImageName, L"cmd.exe") && !wcsstr(wcsImageName, L"powershell.exe"))
143     {
144         puts("Assertion fail. Parent process neither cmd nor powershell.");
145         exit(1);
146     }
147     WCHAR wcsDllName[] = L"HelloWorld.dll";
148     LoadLibraryRemote(hProcess, wcsDllName);
149     FreeLibraryRemote(hProcess, wcsDllName);
150     CloseHandle(hProcess);
151 }

%CC% -shared dllmain.cpp -o HelloWorld.dll
%CC% main.cpp -o HelloWorld.exe