W3C home > Mailing lists > Public > public-webappsec@w3.org > April 2013

RE: CSP and innerHTML

From: Carson, Cory <Cory.Carson@boeing.com>
Date: Tue, 30 Apr 2013 11:30:04 -0700
To: "Hill, Brad" <bhill@paypal-inc.com>, Ian Melven <imelven@mozilla.com>, WebAppSec WG <public-webappsec@w3.org>
Message-ID: <D4054D6F1BC77B409DCE63781532EE8550A215D60A@XCH-NW-21V.nw.nos.boeing.com>
While not strictly existing within a cross-platform specification, Microsoft implemented a similar feature for their browser-based local application runtime: http://msdn.microsoft.com/en-us/library/windows/apps/hh465380.aspx#dynamically_adding_html. 

Would anyone from Microsoft wish to speak to this feature? In particular, does your experience with your Microsoft-only version suggest that it's a good idea to provide a similar feature for CSP?

-----Original Message-----
From: Hill, Brad [mailto:bhill@paypal-inc.com] 
Sent: Tuesday, April 30, 2013 11:17 AM
To: Ian Melven; WebAppSec WG
Subject: RE: CSP and innerHTML

I'm interested in an example attack this would stop, which depends uniquely on inner/outerHTML.

The only use I can think of for this off the top of my head is if you're attempting to use a supervisory script to monitor and approve changes to the DOM  - which the implementation details of innerHTML typically do an end-run around.  Otherwise, isn't innerHTML functionally equivalent to other DOM-based APIs?  (and shouldn't the internal implementation be subject to the same CSP constraints already?)

-Brad

> -----Original Message-----
> From: Ian Melven [mailto:imelven@mozilla.com]
> Sent: Tuesday, April 30, 2013 11:08 AM
> To: WebAppSec WG
> Subject: CSP and innerHTML
> 
> 
> Hi,
> 
> recently Jonas Sicking raised the idea of having a CSP directive that 
> would block usage of innerHTML
> 
> the primary motivation for doing this seems to be additional defence 
> in depth on top of CSP already restricting script and style injections
> 
> i'm curious what others think of this idea and looking for feedback :)
> 
> thanks,
> ian

Received on Tuesday, 30 April 2013 18:31:32 UTC

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