Re: note on gnome shell extensions

[Vincent Danen <vdanen () redhat com>]

* [2012-09-13 18:03:33 +0200] Marcus Meissner wrote:

> On Thu, Sep 13, 2012 at 05:39:57PM +0200, Tavis Ormandy wrote:
> > On Mon, Sep 10, 2012 at 02:48:38PM -0600, Vincent Danen wrote:
> > > * [2012-09-08 18:14:10 -0600] Kurt Seifried wrote:
> > > SUSE has some interesting info in their bug:
> > >
> > > https://bugzilla.novell.com/show_bug.cgi?id=779473#c4
> > >
> > > By the sounds of it, this should be harmless.  Vincent Untz says that
> > > the browser plugin doesn't actually install the extensions, it's passed
> > > to another process via a dbus call to gnome-shell, which sends the uuid
> > > of the extension to the extensions.gnome.org web site in order to
> > > download the extension.
> > >
> > > See:
> > >
> > > http://git.gnome.org/browse/gnome-shell/tree/js/ui/shellDBus.js#n305
> > > http://git.gnome.org/browse/gnome-shell/tree/js/ui/extensionDownloader.js#n27
> > >
> > > which is:
> > >
> > > let message = Soup.form_request_new_from_hash('GET', REPOSITORY_URL_INFO, params);
> > >
> > > And REPOSITORY_URL_INFO is hardcoded earlier:
> > >
> > > const REPOSITORY_URL_BASE = 'https://extensions.gnome.org';
> > > const REPOSITORY_URL_DOWNLOAD = REPOSITORY_URL_BASE + '/download-extension/%s.shell-extension.zip';
> > > const REPOSITORY_URL_INFO     = REPOSITORY_URL_BASE + '/extension-info/';
> > > const REPOSITORY_URL_UPDATE   = REPOSITORY_URL_BASE + '/update-info/';
> > >
> > > I don't think this is something that can be exploited, based on the
> > > above.
> >
> > Not sure I follow the logic, can't I just upload something malicious to
> > extensions.gnome.org and then force you to download it? I mean, I can
> > try it if you're not convinced it's possible.
>
> There are supposed to be reviewers before it gets activated, but exactly
> this concern Sebastian also voiced.
>
> > They surely do not have a magical technique for determining if my code
> > is or can become malicious.
>
> Exactly.

Yeah, this is definitely a possibility, but could happen regardless of
this with some social engineering (hey, download my cool foo extension!)
and have something malicious up there.  This is pretty much the same
thing, just making it easier.

It's not much different than having a malicious app in the
iTunes/Android/Whatever app store.  The flaw there isn't so much in the
app store, but the app.  Wouldn't the same thought apply here?

--
Vincent Danen / Red Hat Security Response Team