Windows Delphi / Indirect Memory Writing

Code

program PoC;

{$APPTYPE CONSOLE}

uses
  Winapi.Windows, System.SysUtils;

begin
  try
    var AString := 'Hello, World';
    var AStringSize := SIZE_T(Length(AString) * SizeOf(WideChar));

    var pDummyBuffer := nil;
    var pNewBuffer := nil;

    GetMem(pDummyBuffer, High(Byte));
    try
      //
      // Example 1: ReadProcessMemory
      //

      // Alloc a new memory region in current process using VirtualAlloc
      pNewBuffer := VirtualAlloc(nil, AStringSize, MEM_COMMIT, PAGE_READWRITE); // +Execute
      if not Assigned(pNewBuffer) then
        raise Exception.Create(Format('VirtualAlloc le:%d', [GetLastError()]));

      // Copy our buffer (string) using an unrelated Windows API (e.g. ReadProcessMemory)
      var pDestOffset : PSIZE_T;

      for var I := 0 to AStringSize -1 do begin
        pDestOffset := Pointer(NativeUInt(pNewBuffer) + I);
        ///

        ReadProcessMemory(GetCurrentProcess(), pNewBuffer, pDummyBuffer, PByte(NativeUInt(AString) + I)^, pDestOffset^);
      end;

      ///
      WriteLn(Format('Indirectly Copied String (ReadProcessMemory): "%s"', [String(PWideChar(pNewBuffer))]));

      //
      // Example 2: ReadFile
      //

      AString := '@DarkCoderSc'; // Keep same size as for "Hello, World" to prevent re-allocating memory for our example

      var hFile := CreateFileW(PWideChar(GetModuleName(0)), GENERIC_READ, FILE_SHARE_READ, nil, OPEN_ALWAYS, 0, 0);
      if hFile = INVALID_HANDLE_VALUE then
        raise Exception.Create(Format('CreateFileW le:%d', [GetLastError()]));
      try
        for var I := 0 to AStringSize -1 do begin
          pDestOffset := Pointer(NativeUInt(pNewBuffer) + I);
          ///

          ReadFile(hFile, PByte(pDummyBuffer)^, PByte(NativeUInt(AString) + I)^, pDestOffset^, nil);
        end;

        ///
        WriteLn(Format('Indirectly Copied String (ReadFile): "%s"', [String(PWideChar(pNewBuffer))]));
      finally
        CloseHandle(hFile);
      end;

      ///
      Readln;
    finally
      if Assigned(pNewBuffer) then
        VirtualFree(pNewBuffer, AStringSize, MEM_RELEASE);

      if Assigned(pDummyBuffer) then
        FreeMem(pDummyBuffer, High(Byte));
    end;
  except
    on E: Exception do
      Writeln(E.ClassName, ' -> Error: ', E.Message);
  end;
end.