Date: Wed, 04 Feb 2015 11:29:27 -0800
From: "Ben Lincoln (F7EFC8C9 - FD)" <F7EFC8C9@...eaththewaves.net>
To: "fulldisclosure@...lists.org" <fulldisclosure@...lists.org>
Cc: bugs@...uritytracker.com, bugtraq@...urityfocus.com, cve-assign@...re.org
Subject: Re: [FD] Major Internet Explorer Vulnerability - NOT Patched

So here's a possibly stupid question: is this entirely an IE flaw, or is 
it tied to the use of Cloudflare by the targeted site as well as the 
attacking site?

I ask because:

1 - I tried to reproduce the attack in a number of ways without using 
CloudFlare, and was unsuccessful.
2 - Since I don't have access to a CloudFlare account, I used Burp to do 
a find/replace for proxied response headers and bodies on 
"www.dailymail.co.uk" and then "dailymail.co.uk" with a target domain 
which does not use Cloudflare, then accessed the Deusen demo page. The 
injection attempt failed.
3 - I then used Burp in the same way, but replaced 
"www.dailymail.co.uk"/"dailymail.co.uk" with a target domain which 
*does* use CloudFlare, and the injection attempt succeeded.

If this is true, am I correct in thinking that while this definitely 
involves a vulnerability in IE, it also depends at least on targeting 
website owners who use JavaScript hosted on shared domains (CloudFlare, 
in this case), which is inherently riskier than hosting it all on one's 
own domain due to the way cross-domain security works in modern browsers?

I don't have time to to a teardown on CloudFlare.JS, but does this also 
depend on some sort of code vulnerability in that file?

Even if one or both of those caveats are true, it's a very impressive 
exploit, but I'd like to make sure the label "universal" is actually 
justified.

Sorry if this has already been discussed elsewhere. I couldn't find 
anything when I looked.

- Ben

On 2015-02-02 12:53, Joey Fowler wrote:
> Hi David,
>
> "nice" is an understatement here.
>
> I've done some testing with this one and, while there *are* quirks, it most
> definitely works. It even bypasses standard HTTP-to-HTTPS restrictions.
>
> As long as the page(s) being framed don't contain X-Frame-Options headers
> (with `deny` or `same-origin` values), it executes successfully. Pending
> the payload being injected, most Content Security Policies are also
> bypassed (by injecting HTML instead of JavaScript, that is).
>
> It looks like, through this method, all viable XSS tactics are open!
>
> Nice find!
>
> Has this been reported to Microsoft outside (or within) this thread?
>
> --
> Joey Fowler
> Senior Security Engineer, Tumblr
>
>
>
> On Sat, Jan 31, 2015 at 9:18 AM, David Leo <david.leo@...sen.co.uk> wrote:
>
>> Deusen just published code and description here:
>> http://www.deusen.co.uk/items/insider3show.3362009741042107/
>> which demonstrates the serious security issue.
>>
>> Summary
>> An Internet Explorer vulnerability is shown here:
>> Content of dailymail.co.uk can be changed by external domain.
>>
>> How To Use
>> 1. Close the popup window("confirm" dialog) after three seconds.
>> 2. Click "Go".
>> 3. After 7 seconds, "Hacked by Deusen" is actively injected into
>> dailymail.co.uk.
>>
>> Technical Details
>> Vulnerability: Universal Cross Site Scripting(XSS)
>> Impact: Same Origin Policy(SOP) is completely bypassed
>> Attack: Attackers can steal anything from another domain, and inject
>> anything into another domain
>> Tested: Jan/29/2015 Internet Explorer 11 Windows 7
>>
>> If you like it, please reply "nice".
>>
>> Kind Regards,
>>
>>
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