How to clean up __proto__ (was: Why we need to clean up __proto__)

Russell Leggett russell.leggett at gmail.com
Fri Dec 30 08:07:39 PST 2011


On Fri, Dec 30, 2011 at 6:53 AM, David Bruant <bruant.d at gmail.com> wrote:

>  Le 30/12/2011 02:28, John J Barton a écrit :
>
> On Thu, Dec 29, 2011 at 5:11 PM, David Bruant <bruant.d at gmail.com> wrote:
>
>> Le 30/12/2011 01:00, Lasse Reichstein a écrit :
>> > On Thu, Dec 29, 2011 at 8:41 PM, Mark S. Miller <erights at google.com>
>> wrote:
>>  I've been thinking about this "run first" idea for some time. Since on a
>> webpage, security seems to depend on your ability to run code first, it
>> would be interesting if there was a way to ensure that some code
>> (preferably defensive) is run before *any* other code. Though I find
>> this interesting, I'm still not sure whether this would be a good or bad
>> idea. I'm also clueless on how it would look like.
>> Creative ideas welcome.
>>
>
> The browser runs first: what can't it do that you want to support?
>
> I was thinking of the case of XSS for instance where your code is in
> competition with unexpected and malicious code. What I've said before
> applies and even against an XSS attack, you can prevent cookie theft as
> long as you run first.
> I can't see a way for the browser to enforce that trusted code run before
> untrusted code.
>
> I must be missing something here, but if you put your defensive script
first in the head of the html, how can XSS code run first? Most XSS attacks
are base on user data unescaped and put into the body of the page
somewhere. As long as server-side html generation never inserts unescaped
code into the head before the defensive script code, where is the
vulnerability. I'm not saying I'm right, I just don't see it.

- Russ
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