W3C home > Mailing lists > Public > whatwg@whatwg.org > December 2016

Re: [whatwg] window.opener security issues (Was: WhatWG is broken)

From: Michael A. Peters <mpeters@domblogger.net>
Date: Thu, 1 Dec 2016 18:42:56 -0800
To: whatwg@lists.whatwg.org
Message-ID: <701c99fb-264f-fc08-d41e-50d87253e237@domblogger.net>
Well if it was done as a header, I suppose it could be added as a 
http-equiv meta tag for those who want to.

Header is the easiest solution to make sure it is applied everywhere 
without question. It could even be added at the front-end proxy to cover 
numerous web applications on many domains at once.

And I know this is conspiracy theory, but that's why I think there is 
such resistance to it.

Since the flaw is required for OAuth to work, companies invested in 
OAuth and that profit from OAuth solutions don't want sites behind 
proxies that would break OAuth and don't want webmasters to understand 
they have to reduce security in order to implement an OAuth solution.

That's just a suspicion of mine, but I can't think of any other logical 
reason as to why a node attribute was chosen as the solution, and why 
there is such resistance to doing it the right way with a header. To me 
it just doesn't make sense.

On 12/01/2016 05:45 PM, Zac Spitzer wrote:
> how about rather than requiring this on every <a> why not support a base
> tag directive
> for the whole document i.e. <base rel="noopener">, similar to <base
> target="_blank">?
>
> On Fri, Dec 2, 2016 at 12:39 PM, Domenic Denicola <d@domenic.me> wrote:
>
>> From: whatwg [mailto:whatwg-bounces@lists.whatwg.org] On Behalf Of Ian
>> Hickson
>>
>>> I believe that's a bit of an overstatement. There are certainly risks
>> involved in window.opener (they're briefly discussed in the spec itself),
>> but it doesn't remove the origin checks.
>>
>> This is the crucial point.
>>
>> Whenever you are discussing a supposed security issue, you need to make
>> clear what the threat model is. That is:
>>
>> - What would be the impact on the victim if the security hole is taken
>> advantage of?
>> - Is this something we are trying to prevent on the web platform?
>>
>> In this case, the impact on the victim (a user of a web browser) is that
>> they could click a link from page A to page B, which opens in a new tab
>> (tab B). Then, tab A could be navigated to a new URL, instead of staying on
>> page A.
>>
>> This is not a big impact. Notably, page B is not able to read any of the
>> content of page A, which might be sensitive. Page B is not able to
>> interfere with the operation of any of page B's scripts. And crucially,
>> when page B navigates tab A to another page, the URL bar of tab A changes
>> to indicate that.
>>
>> There is no desired security guarantee on the platform that we want to
>> prevent pages from directing users to "bad" sites. We count on users
>> inspecting the URL bar to understand what page they are interacting with in
>> a given tab.
>>
>> So, while it might be a bit surprising that suddenly tab A is navigating
>> somewhere else, there is no security issue here, and users are not
>> endangered in any way---at least, not in any more danger than they already
>> are from browsing the web without looking at their URL bar to see where
>> they've ended up at.
>>
>
>
>
Received on Friday, 2 December 2016 02:43:29 UTC

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