On Saturday, October 29, 2016, Daniel Friesen daniel@nadir-seen-fire.com wrote:
On 2016-10-29 8:40 AM, Brian Wolff wrote:
On Sat, Oct 29, 2016 at 2:50 PM, Dr. Michael Bonert michael@librepathology.org wrote:
Hello,
I was wondering about the security of Widgets ( https://www.mediawiki.org/wiki/Extension:Widgets ) that get parameters passed to them. Any thoughts?
Are the parameters passed through to the widget cleansed of
html/scripts?
If it isn't -- is it possible to easily enforce typing/boundaries on the parameters?
There is no way to abstractly ensure scripts are cleaned from text. If you know exactly where it is going you may be able to escape everything. But you cannot target scripting explicitly and expect to clean it up, as there are numerous tricks that can be used to bypass anything but the strictest of escaping: https://www.owasp.org/index.php/XSS_Filter_Evasion_Cheat_Sheet
Create page: Widget:OpenSeadragon
<noinclude>__NOTOC__
<!-- Copyright (c) 2016 Michael Bonert -->
<!-- Released under GNU General Public Licence - Version 3; see http://www.gnu.org/licenses/gpl.html -->
To insert this widget, use the following code:
<nowiki>{{#widget:</nowiki>{{PAGENAME}}<nowiki> |image=12881.dzi |width=800 |height=600 }}</nowiki>
</noinclude> <includeonly><!-- This inserts an OpenSeadragon image --> <div id="openseadragon1" style="width: <!--{$width|default:400|escape:'html'}-->px; height: <!--{$height|default:300|escape:'html'}-->px;"></div> <script src="../../openseadragon/openseadragon.min.js"></script> <script type="text/javascript"> var viewer = OpenSeadragon({ id: "openseadragon1", prefixUrl: "../../openseadragon/images/", tileSources: "../../vslide/<!--{$image|escape:'urlpathinfo'}-->" }); </script> </includeonly> -------------------------------------------------
In theory that's what the escape modifier is for in smarty parameters.
However, in this example, <!--{$width|default:400|escape:'html'}-->px; inside a style attribute isn't really sufficient, as a user could set a width parameter like "400; behavior: url( 'https://foo.com/bar.htc#baz' );x: ", which would cause javascript execution on IE9 and older. (There are other properties for other browsers, however mostly affecting only older browsers). You could also leak private info about your users by doing something like background-image: url( "http://external.com/foo.png" ) .
[Disclaimer: I have not read the source code of the widgets extension, so there could also potentially be generic security issues with the extension. Since I haven't reviewed it, I don't really know].
-- bawolff
And then there is $image. urlpathinfo doesn't escape quotes, backslashes, or </script>.
Its hard to find docs on what urlpathinfo actually does (talk about a red flag for a security mechanism...) but i thought it was basically rawurlencode, which i think escapes all the relavent characters in this context as percent encoding.
-- Bawolff