>The issue is that they apply the same escaping, regardless of the
>html context. So, in Twig and mustache, <div class={{something}}></div> is
>vulnerable, if something is set to "1234 onClick=doSomething()".
Right, the engine would render:
<div class=1234 onClick=doSomething()> </div>
because it only escapes HTML by default.
Now, note that the problem can be fixed with <div class={{makeStringSafe
something}}>
Where "makestringSafe" is a function defined by us and executed there that
escapes to our liking.
This is equivalent to what we would need to do in PHP
server side if we used PHP native templating.
We would need to implement an escaping function like "makeStringSafe" that
we would execute like:
<div class="View::makeStringSafe($this->something)"></div>
What I wanted to clarify (regarding Sumana's first e-mail) is that when it
comes to security we would need to take the same precautions with a string
based javascript engine than we would do with any PHP engine we choose.
Namely, as you said, spot the lack of "makestringSafe" via CRs.
To be completely fair, the "makeStringSafe" could be inserted with a
build/template compilation process and thus we would not need CRs but
rather we could rely on automation.
On Wed, Mar 26, 2014 at 2:43 PM, Chris Steipp <cste...@wikimedia.org> wrote:
> On Wed, Mar 26, 2014 at 3:21 AM, Nuria Ruiz <nu...@wikimedia.org> wrote:
>
> > >So for string-based systems to be
> > >as safe as dom ones, we also need a layer of policy and code review that
> > we
> > >might not need with a dom-based system.
> > String based template engines (like handlebars) do escape as a default,
> you
> > have to use "special" markup for it not to escape. Can you explain in
> more
> > detail what is the security concern with those?
> >
>
> Correct. The issue is that they apply the same escaping, regardless of the
> html context. So, in Twig and mustache, <div class={{something}}></div> is
> vulnerable, if something is set to "1234 onClick=doSomething()". So
> policy/code review is needed to say that attributes with user-supplied data
> must be quoted in a way compatible with the templating engine (' or " for
> Twig, " for Mustache since Mustache doesn't escape single quotes).
>
>
> >
> >
> >
> >
> >
> > On Wed, Mar 19, 2014 at 7:51 PM, Chris Steipp <cste...@wikimedia.org>
> > wrote:
> >
> > > On Tue, Mar 18, 2014 at 8:27 PM, Sumana Harihareswara <
> > > suma...@wikimedia.org
> > > > wrote:
> > >
> > > > I'm trying to understand what our current situation is and what our
> > > > choices are around HTML templating systems and MediaWiki, so I'm
> gonna
> > > > note what I think I understand so far in this mail and then would
> love
> > > > for people to correct me. TL;DR - did we already consense on a
> > > > templating system and I just missed it?
> > > >
> > > > Description: An HTML templates system (also known as a templating
> > > > engine) lets you (the programmer) write something that looks more
> like
> > a
> > > > document than it looks like code, then has hooks/entry points/macro
> > > > substitution points (for user input and whatnot) that then invoke
> code,
> > > > then emits finished HTML for the browser to render.
> > > >
> > > > Examples: PHP itself is kinda a templating language. In the PHP
> world,
> > > > Smarty is a somewhat more mature/old-school choice. Mustache.js is a
> > > > popular modern choice. And in other languages, you'd pick a lot of
> the
> > > > MVC frameworks that are popular, e.g. Django or Jinja in Python.
> > > >
> > > > Spectrum of approaches: One approach treats HTML as a string
> ("here's a
> > > > bunch of bytes to interpolate"). From a security perspective, this is
> > > > dangerously easy to have vulnerabilities in, because you just naively
> > > > insert strings. Then on the other end of the spectrum, you have code
> > > > that always keeps the document object model (DOM) in memory, so the
> > > > programmer is abstractly manipulating that data model and passing
> > around
> > > > an object. Sure, it spits out HTML in the end, but inherent in the
> > > > method for turning those objects into HTML is a sanitization step, so
> > > > that's inherently more secure. There's some discussion at
> > > > https://www.mediawiki.org/wiki/Parsoid/Round-trip_testing/Templates.
> > I
> > > > presume we want the latter, but that the former model is more
> > performant?
> > > >
> > >
> > > I don't want to build too much of a straw man against string-based
> > systems,
> > > so it's probably more appropriate to say that the same escaping is
> > applied
> > > to all strings regardless of the html context, or the developer is
> > > responsible for applying custom escaping. So for string-based systems
> to
> > be
> > > as safe as dom ones, we also need a layer of policy and code review
> that
> > we
> > > might not need with a dom-based system.
> > >
> > > Performance of the dom-based systems has turned out to be not that bad,
> > but
> > > performance is a major factor in any engine we go with.
> > >
> > >
> > >
> > > >
> > > > We talked about this stuff in
> > > >
> > >
> >
> https://www.mediawiki.org/wiki/Architecture_meetings/RFC_review_2014-02-21
> > > > and
> > > >
> > > >
> > >
> >
> https://www.mediawiki.org/wiki/Talk:Architecture_Summit_2014/HTML_templating#Wrap_up:_Next_steps
> > > > . Based on that plus
> > > >
> > > >
> > >
> >
> https://www.mediawiki.org/wiki/Architecture_Summit_2014/RFC_clusters#HTML_templating
> > > > it seems like we are supposed to get consensus on which system(s) to
> > > > use, and we kind of have four things we could choose:
> > > >
> > > > * oojs - https://www.mediawiki.org/wiki/OOjs_UI -- could use this
> > > > toolkit with one of the template approaches below, or maybe this is
> > > > enough by itself! Currently used inside VisualEditor and I am not
> sure
> > > > whether any other MediaWiki extensions or teams are using it? This
> is a
> > > > DOM-based templating system.
> > > >
> > > > Template approaches which are competing?:
> > > > * MVC framework - Wikia has written their own templating library that
> > > > Wikia uses (Nirvana). Owen Davis is talking about this tomorrow in
> the
> > > > RFC review meeting.
> > > > https://www.mediawiki.org/wiki/Requests_for_comment/MVC_framework
> > > > * mustache.js stuff - Ryan Kaldari and Chris Steipp mentioned this I
> > > think?
> > > > * Knockout-compatible implementation in Node.js & PHP
> > > >
> > > >
> > >
> >
> https://www.mediawiki.org/wiki/Requests_for_comment/HTML_templating_library/KnockoutProposal#Longer-term_architecture
> > > > and
> > > >
> > > >
> > >
> >
> https://www.mediawiki.org/wiki/Requests_for_comment/HTML_templating_library/Knockoff_-_Tassembly
> > > > , being worked on by Gabriel Wicke, Matt Walker, and others.
> DOM-based.
> > > >
> > >
> > >
> > > I think
> > >
> > >
> >
> https://www.mediawiki.org/wiki/Requests_for_comment/HTML_templating_librarycaptures
> > > most of the current thinking. While Knockoff is being developed,
> > > Handlebars (and the php port of it) seems to be the leader for a
> > > string-based solution.
> > >
> > >
> > > >
> > > > There's also an OutputPage refactor suggested in
> > > >
> > https://www.mediawiki.org/wiki/Requests_for_comment/OutputPage_refactor
> > > > that's part of the HTML Templating RFC Cluster
> > > >
> > > >
> > >
> >
> https://www.mediawiki.org/wiki/Architecture_Summit_2014/RFC_clusters#HTML_templating
> > > > .
> > > >
> > > > I guess my biggest question right now is whether I have all the big
> > > > moving parts right in my summary above. Thanks.
> > >
> > >
> > > > --
> > > > Sumana Harihareswara
> > > > Senior Technical Writer
> > > > Wikimedia Foundation
> > > >
> > > > _______________________________________________
> > > > Wikitech-l mailing list
> > > > Wikitech-l@lists.wikimedia.org
> > > > https://lists.wikimedia.org/mailman/listinfo/wikitech-l
> > > _______________________________________________
> > > Wikitech-l mailing list
> > > Wikitech-l@lists.wikimedia.org
> > > https://lists.wikimedia.org/mailman/listinfo/wikitech-l
> > >
> > _______________________________________________
> > Wikitech-l mailing list
> > Wikitech-l@lists.wikimedia.org
> > https://lists.wikimedia.org/mailman/listinfo/wikitech-l
> >
> _______________________________________________
> Wikitech-l mailing list
> Wikitech-l@lists.wikimedia.org
> https://lists.wikimedia.org/mailman/listinfo/wikitech-l
>
_______________________________________________
Wikitech-l mailing list
Wikitech-l@lists.wikimedia.org
https://lists.wikimedia.org/mailman/listinfo/wikitech-l
