defaultcontroller.php

См. документацию.

<?php
 
namespace Bitrix\Main\Engine;
 
 
class DefaultController extends Controller
{
    public function configureActions()
    {
        return array(
            'index' => array(
                'prefilters' => array(
                    new ActionFilter\Authentication,
                    new ActionFilter\HttpMethod(array('GET')),
                ),
            ),
        );
    }
 
    public function indexAction()
    {
        return "It's default behavior";
    }
}