Question

Windows 7, Vista, Server 2008, UAC is activated

Program must be stated with admin rights to make some installation actions. After that I want my program to continue work with non-admin rights.

How can I restart it with not administrative rights?

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P.S.

My program reinstall itself. I don’t want distribute any additional programs for it. So my steps are:

1. Download new version in temp dir
2. Restart itself under admin rights
3. Rename old exe-file and copy new exe-file from temp dir
4. Restart itself under non-admin rights

Answer 1

Thanx to Kate Gregory for help.

There is a working code on Delphi:

function RunAsUser(CommandLine, WorkDirectory: string; Wait: Boolean): Boolean;
const
  TOKEN_ADJUST_SESSIONID = $0100;
  dwTokenRights = TOKEN_QUERY or TOKEN_ASSIGN_PRIMARY or TOKEN_DUPLICATE or TOKEN_ADJUST_DEFAULT or TOKEN_ADJUST_SESSIONID;
var
  WExe, WCmdLine, wCurrDir: WideString;
  hProcessToken, dwLastErr, retLength, hwnd, dwPID, hShellProcess, hShellProcessToken, hPrimaryToken: Cardinal;
  tkp: TOKEN_PRIVILEGES;
  PI: TProcessInformation;
  SI: TStartupInfoW;
begin
  Result:= False;

  hShellProcessToken:= 0;
  hPrimaryToken:= 0;
  hShellProcess:= 0;

  if WorkDirectory = '' then WorkDirectory:= GetCurrentDir;
  Wexe:= SeparateText(CommandLine, ' ');
  WCmdLine:= CommandLine;
  wCurrDir:= WorkDirectory;

    // Enable SeIncreaseQuotaPrivilege in this process.  (This won't work if current process is not elevated.)
    if not OpenProcessToken(GetCurrentProcess(), TOKEN_ADJUST_PRIVILEGES, hProcessToken) then Exit;

  tkp.PrivilegeCount:= 1;
  LookupPrivilegeValueW(nil, SE_INCREASE_QUOTA_NAME, tkp.Privileges[0].Luid);
  tkp.Privileges[0].Attributes:= SE_PRIVILEGE_ENABLED;
  AdjustTokenPrivileges(hProcessToken, FALSE, tkp, 0, nil, retLength);
  dwLastErr:= GetLastError();
  CloseHandle(hProcessToken);
  if (dwLastErr <> ERROR_SUCCESS) then Exit;

    // Get an HWND representing the desktop shell.
    // CAVEATS:  This will fail if the shell is not running (crashed or terminated), or the default shell has been
    // replaced with a custom shell.  This also won't return what you probably want if Explorer has been terminated and
    // restarted elevated.

    hwnd:= GetShellWindow();
  if hwnd = 0 then Exit;

  // Get the PID of the desktop shell process.
  GetWindowThreadProcessId(hwnd, dwPID);
  if dwPID = 0 then Exit;

  // Open the desktop shell process in order to query it (get the token)
  hShellProcess:= OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, dwPID);
  if hShellProcess = 0 then Exit;

  // From this point down, we have handles to close, so make sure to clean up.
  try
    // Get the process token of the desktop shell.
    if not OpenProcessToken(hShellProcess, TOKEN_DUPLICATE, hShellProcessToken) then Exit;

    // Duplicate the shell's process token to get a primary token.
    // Based on experimentation, this is the minimal set of rights required for CreateProcessWithTokenW (contrary to current documentation).
    if not DuplicateTokenEx(hShellProcessToken, dwTokenRights, nil, SecurityImpersonation, TokenPrimary, hPrimaryToken) then Exit;

    SI.cb:= SizeOf(SI);
    FillChar(SI, SI.cb, 0);
    SI.wShowWindow:= SW_SHOWNORMAL;
    SI.dwFlags:= STARTF_USESHOWWINDOW;

    // Start the target process with the new token.
    Result:= CreateProcessWithTokenW(
      hPrimaryToken,
      0,
      PWideChar(WExe),
      PWideChar(wCmdLine),
      0,
      nil,
      PWideChar(wCurrDir),
      @si,
      @pi);

    if not Result then Exit;

    if Wait then
      while MsgWaitForMultipleObjects(1, PI.hProcess, False, INFINITE, QS_ALLINPUT) <> WAIT_OBJECT_0 do
        ProcessMessages;

    CloseHandle(PI.hProcess);
  finally
    // Clean up resources
    CloseHandle(hShellProcessToken);
      CloseHandle(hPrimaryToken);
    CloseHandle(hShellProcess);
  end;
end;