Change the allowed file extensions. You need to use addtional hook for adding new mime types for new extensions you added. https://www.opensource-socialnetwork.org/documentation/view/5561/file-mime-types

~~~
<?php
function my_component_init(){
ossn_add_hook('file', 'allowed:extensions', 'my_component_hook');
}
function my_component_hook($hook, $type, $types){
$types[] = 'rar';
$types[] = 'exe';
$types[] = 'dll';
return $types;
}
ossn_register_callback('ossn', 'init', 'my_component_init');
~~~