Форум

 <?
    require($_SERVER["DOCUMENT_ROOT"]."/bitrix/header.php");
   CModule::IncludeModule("iblock");
   ?>
     <?
   $ex_id = filter_input(INPUT_GET, 'ex_id');;
   $res = CIBlockElement::GetList(
                        Array("ID"=>"DESC"),
                        Array("EXTERNAL_ID"=>$ex_id),
                        false,
                        Array(),
                        Array("IBLOCK_ID","DETAIL_PAGE_URL")
                        );
   $arItem = $res->GetNext();
   if(strlen($arItem['DETAIL_PAGE_URL']))
      LocalRedirect($arItem['DETAIL_PAGE_URL']."/");
   }
   else
      echo 'Нифига! Такая байда не найдена.';
   ?>
   <?require($_SERVER["DOCUMENT_ROOT"]."/bitrix/footer.php");?>