We don't want to use Microsoft's,
whatever we do, because it promotes
own borked browser IE9.
On Fri, Jun 3, 2011 at 11:30 AM, Mark Dilley <markwdilley(a)gmail.com>
<aside from main conversation>
Would it be a good community gesture to join Microsoft in trying to
or to not join them and put up a more general banner
and move on?
</aside from main conversation>
On 03Jun2011, at 10:53 AM, Brion Vibber wrote:
> On Thu, Jun 2, 2011 at 5:21 PM, Tim Starling <tstarling(a)wikimedia.org
>> On 03/06/11 06:56, Brion Vibber wrote:
>>> For 1) I'm honestly a bit willing to sacrifice a few IE 6 users at
>>> point; the vendor's dropped support, shipped three major versions,
>>> actively campaigning to get the remaining users to upgrade. :) But I
>>> protecting, so if we can find a workaround that's ok.
>> We can't really do this without sending "Vary: User-Agent", which
>> would completely destroy our cache hit ratio. For people who use
>> with our X-Vary-Options patch, it would be possible to use a very
>> X-Vary-Options header to single out IE 6 requests, but not everyone
>> has that patch.
> I'm really thinking more along the lines of: if someone's an IE
> user they have hundreds of other exploit vectors staring them in the
> too, and we can't protect them against many of them -- or ANY of them
> they're visiting other sites than just an up-to-date MediaWiki.
> The cost of this fix has been immense; several versions of the fix
> varying levels of disruption on production sites, both for IE 6 users
> non-IE 6 users, and several weeks of delay on the 1.17.0 release.
> I'd be willing to accept a few drive-by downloads for IE 6 users; it's
> ideal but it's something that their antivirus tools etc will already
> watching out for, that end-users already get trained to beware of, and
> will probably *still* be exploitable on other web sites that they
> The main issue here is that we don't a wide variety of web servers set
>> up for testing. We know that Apache lets you detect %2E versus dot
>> $_SERVER['REQUEST_URI'], but we don't know if any other web servers
>> Note that checking for %2E alone is not sufficient, a lot of
>> installations (including Wikimedia) have an alias /wiki ->
>> /w/index.php which can be used to exploit action=raw.
> Well that should be fine; as long as we can see the "/wiki?/foo.bat"
> can identify that it doesn't contain an unencoded dot in the path.
> It sounds like simply checking REQUEST_URI when available would
> huge portion of our false positives that affect real-world situations.
> Apache is still the default web server in most situations for most
> and of course runs our own production servers.
>>> Are there any additional exploit vectors for API output other than
>>> mixed unescaped into JSON?
>> Yes, all other content types, as I said above.
> Only as drive-by downloads, or as things that execute without
>> I think the current solution in trunk, plus the redirect idea that
>> I've been discussing with Roan, is our best bet for now, unless
>> someone wants to investigate $_SERVER['REQUEST_URI'].
> *nod* Checking REQUEST_URI is probably the first thing we should do
> it's available.
>> If there is an actual problem with ForeignAPIRepo then we can look at
>> server-side special cases for it. But r89248 should allow all API
>> requests that have a dotless value in their last GET parameter, and a
>> quick review of ForeignAPIRepo in 1.16 and trunk indicates that it
>> always sends such requests.
> Yay! That's one less thing to worry about. :D
>> Since we're talking about discarded solutions for this, maybe it's
>> worth noting that I also investigated using a Content-Disposition
>> header. The vulnerability involves an incorrect cache filename, and
>> it's possible to override the cache filename using a
>> Content-Disposition "filename" parameter. The reason I gave up on it
>> is because we already use Content-Disposition for wfStreamFile():
>> header( "Content-Disposition:
>> inline;filename*=utf-8'$wgLanguageCode'" . urlencode( basename(
>> ) ) );
>> IE 6 doesn't understand the charset specification, so it ignores the
>> header and goes back to detecting the extension.
> Good to know.
> -- brion
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