winapi - SendInput 在 UAC 提示时失败

Question

我们正在编写一个只运行的远程桌面应用程序，它使用 SendInput 进行键盘(和鼠标)交互。但是它不能与 UAC 提示交互。

我们的应用为此需要哪些许可/权利？

背景信息:该应用程序是由另一个复制 winlogon.exe 访问 token 的进程生成的。这允许在具有系统完整性级别的 SYSTEM 帐户下运行，附加到物理控制台 session 并具有与 winlogon.exe ( https://learn.microsoft.com/en-us/windows/desktop/secauthz/privilege-constants) 相同的 SE 权限，尽管并非所有这些都已启用。

struct MY_TOKEN_PRIVILEGES {
  DWORD PrivilegeCount;
  LUID_AND_ATTRIBUTES Privileges[2];
};

int RunUnderWinLogon(LPCWSTR executableWithSendInput)
{
  DWORD physicalConsoleSessionId = WTSGetActiveConsoleSessionId();

  auto winlogonPid = GetWinLogonPid(); // external function

  if (!winlogonPid)
  {
    std::cout << "ERROR getting winlogon pid" << std::endl;
    return 0;
  }

  HANDLE hWinlogonToken, hProcess;
  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, &hWinlogonToken))
  {
    printf("Process token open Error: %u\n", GetLastError());
  }

  // Is security descriptor needed for SendInput?
  PSECURITY_DESCRIPTOR pSD = NULL;

  SECURITY_ATTRIBUTES saToken;
  ZeroMemory(&saToken, sizeof(SECURITY_ATTRIBUTES));

  saToken.nLength = sizeof (SECURITY_ATTRIBUTES);
  saToken.lpSecurityDescriptor = pSD;
  saToken.bInheritHandle = FALSE;

  HANDLE hWinlogonTokenDup;
  if (!DuplicateTokenEx(hWinlogonToken, TOKEN_ALL_ACCESS, &saToken, SecurityImpersonation, TokenPrimary, &hWinlogonTokenDup))
  {
    printf("DuplicateTokenEx Error: %u\n", GetLastError());
  }

  if (!SetTokenInformation(hWinlogonTokenDup, TokenSessionId, (void*)physicalConsoleSessionId, sizeof(DWORD)))
  {
    printf("SetTokenInformation Error: %u\n", GetLastError());
  }

  //Adjust Token privilege
  LUID luidSeDebugName;
  if (!LookupPrivilegeValue(NULL, SE_DEBUG_NAME, &luidSeDebugName))
  {
    printf("Lookup Privilege value Error: %u\n", GetLastError());
  }

  LUID luidSeTcbName;
  if (!LookupPrivilegeValue(NULL, SE_TCB_NAME, &luidSeTcbName))
  {
    printf("Lookup Privilege value Error: %u\n", GetLastError());
  }

  MY_TOKEN_PRIVILEGES tp;
  tp.PrivilegeCount = 2;
  tp.Privileges[0].Luid = luidSeDebugName;
  tp.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;

  tp.Privileges[1].Luid = luidSeTcbName;
  tp.Privileges[1].Attributes = SE_PRIVILEGE_ENABLED;

  if (!AdjustTokenPrivileges(hWinlogonTokenDup, FALSE, (PTOKEN_PRIVILEGES)&tp, /*BufferLength*/0, /*PreviousState*/(PTOKEN_PRIVILEGES)NULL, NULL))
  {
    printf("Adjust Privilege value Error: %u\n", GetLastError());
  }

  if (GetLastError() == ERROR_NOT_ALL_ASSIGNED)
  {
    printf("Token does not have the privilege\n");
  }

  DWORD creationFlags;
  creationFlags = NORMAL_PRIORITY_CLASS | CREATE_NEW_CONSOLE;

  LPVOID pEnv = NULL;
  if (CreateEnvironmentBlock(&pEnv, hWinlogonTokenDup, TRUE))
  {
    std::cout << "CreateEnvironmentBlock() success" << std::endl;
    creationFlags |= CREATE_UNICODE_ENVIRONMENT;
  }

  SECURITY_ATTRIBUTES saProcess, saThread;
  ZeroMemory(&saProcess, sizeof(SECURITY_ATTRIBUTES));
  ZeroMemory(&saThread, sizeof(SECURITY_ATTRIBUTES));

  saProcess.nLength = sizeof (SECURITY_ATTRIBUTES);
  saProcess.lpSecurityDescriptor = pSD;
  saProcess.bInheritHandle = FALSE;

  saThread.nLength = sizeof (SECURITY_ATTRIBUTES);
  saThread.lpSecurityDescriptor = pSD;
  saThread.bInheritHandle = FALSE;

  STARTUPINFO si;
  ZeroMemory(&si, sizeof(STARTUPINFO));
  si.cb = sizeof(STARTUPINFO);
  si.lpDesktop = (LPWSTR)L"winsta0\\default";

  PROCESS_INFORMATION pi;
  ZeroMemory(&pi, sizeof(pi));

  BOOL bResult = CreateProcessAsUser(
    hWinlogonTokenDup,   // client's access token
    executableWithSendInput,    // file using SendInput
    NULL,                 // command line
    &saProcess,            // pointer to process SECURITY_ATTRIBUTES
    &saThread,               // pointer to thread SECURITY_ATTRIBUTES
    FALSE,              // handles are not inheritable
    creationFlags,     // creation flags
    pEnv,               // pointer to new environment block
    NULL,               // name of current directory
    &si,               // pointer to STARTUPINFO structure
    &pi                // receives information about new process
  );
}

Answer 1

SendInput，与 SendMessage 和 PostMessage 一样，仅限于在与目标进程相同的登录 session 和相同桌面内的进程之间工作。 UAC 提示显示在 Winlogon's Secure Desktop 中(winsta0\Winlogon) 所以你需要使用 OpenInputDesktop() 定期轮询当前桌面，然后使用 SetThreadDesktop() 启用当前线程发送消息发送到用户的桌面/安全桌面，以事件的为准。

在 UAC 的情况下，您需要在系统帐户下运行您的进程，以遵守 UIPI Integrity Level check ，正如您已经做过的那样。

See also: How to switch a process between default desktop and Winlogon desktop?