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Content-Type: multipart/alternative; boundary=001a1136c098c9dc5604f19f45d9
Subject: Re: [PHP-DEV] [RFC] Improve HTML escape
From: yohgaki@ohgaki.net (Yasuo Ohgaki)

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Hi Padraic,

On Wed, Feb 5, 2014 at 6:22 AM, P=C3=A1draic Brady <padraic.brady@gmail.com=
>wrote:

> Doing a bit of due diligence, the reason the forward slash was added
> was to prevent any possibility of someone introducing a Javascript
> comment into an attribute. It's very sketchy, but the theory is that
> since html escaping won't escape /, using html escaping on a
> javascript attribute like onmouseover might allow the browser to
> interpret a comment, disregard the terminating quotes of an attribute,
> and then inject HTML. Personally, it seems a bit garbled - user input
> in a Javascript attribute should be escaped as a Javascript string
> literal with no input injected as actual Javascript code - so it would
> require both a severe browser parsing issue AND a lack of proper
> contextual escaping.
>

It depends on how HTML parser parse HTML.

<tag onmouseover=3D"user_code_here; /*"><tag foo=3D"*/; evil_code_here;">
<tag onmouseover=3Duser_code_here;/* ><tag foo=3D*/; evil_code_here; >

If parser aware the "/*" as JS comment, then it can be attacked.
'/' escape would prevent malicious code to attack when user has sloppy
validation and/or filter.
(HTML parser should parse HTML document as HTML at first and should not
 recognize JS elements and/or anything else, but who knows every parser out
 there is implemented correctly)

I've added deprecation of ENT_COMPAT/ENT_QUOTES to the RFC.

 Is it ready to vote?
No more issues to discuss?
Anyone?

Regards,

--
Yasuo Ohgaki
yohgaki@ohgaki.net

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