Re: Vulnerability by loading doctype-declaration of xml

On Wed, 29 Feb 2012 19:30:15 +0100, Simon Schick <simonsimcity@googlemail.com> wrote:

I just read this post about a vulnerability by loading doctype-declaration of an xml-string given in a request: http://www.idontplaydarts.com/2011/02/scanning-the-internal-network-using-simplexml/ Would it be a good point to restrict which urls can be loaded in the doctype, or is the following line the only possibility to prevent it in a good way? libxml_disable_entity_loader(true);

In PHP 5.4, you can use libxml_set_external_entity_loader() and define your own logic. I'm afraid it's not documented yet, but it receives a callback that takes two strings, a public id and system id and a context (an array with four keys). The callback should return a resource, a string from which a resource can be opened, or NULL. -- Gustavo Lopes