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Date: Wed, 17 Dec 2014 14:24:11 -0600
From: Grandma Eubanks <tborland1@...il.com>
To: oss-security@...ts.openwall.com
Subject: Re: What is the "Grinch" polkit/wheel group issue?
The reason this was not reported was because this was expected behavior. I
didn't feel it needed to be reported because of this and that it is really
a surface opening stager and by itself nothing much. The example posed that
I tried to stress was tended towards home users, not servers. However,
words have been said and 'definitions' needed to be made and it snowballed
into something crazy. An example of how I've been using this:
User is compromised via client-side exploit such as browser, flash, mail
client, etc.
User is running up to date kernel and you don't want to rely on tricks like
.bashrc to trick the user into giving password.
You have access to a new surface area of any package in their repo to
install and exploit to escalate privileges. Of course, you can also install
a package for a new vulnerability released. Especially for people with only
stable repos as it takes a bit for those updates to come across.
**This was important to me because I kept finding vulns in packages no one
is using, but this opened up potentiality for a lot of useless stuff I've
been keeping. I wrote this mainly for them if they're in the same position.
This was the scenario I have been using this for before an article was even
drafted. Most of the other operations require giving a password, like
removing packages, but installing packages does not require anything but to
be in the proper group.
I don't think it requires a CVE, again why I didn't report it, I do however
think it should at least require authentication like every other operation
requires.
Now, the confusion that it was reported is coming from something else
that's I'm going to talk about in January. Something that, again, I'm not
sure is CVE worthy, but could be debatable:
https://bugzilla.redhat.com/show_bug.cgi?id=1128400
On Wed, Dec 17, 2014 at 12:38 PM, Dean Pierce <pierce403@...il.com> wrote:
>
> The key here is the line:
>
> "In order to exploit this, all we need is a single vulnerability in
> any package in a repo. There are tons to choose from. If we type
> ‘PKCon’ or simply ‘man PKCon,’ we can find a list of repos in use and
> then pull a list of all bins and version numbers. I won’t provide one
> here because you don’t want everything handed to you."
>
> Had they actually found a package they could leverage to get root,
> then this would absolutely be a vulnerability, but they didn't. While
> configuring pkcon to allow admins to install packages without typing
> in a password *is* something that might be unexpected for people
> unfamiliar with polkit, that is the exact type of use case it was
> built for.
>
> - DEAN
>
> On Wed, Dec 17, 2014 at 10:24 AM, Kurt Seifried <kseifried@...hat.com>
> wrote:
> > On 17/12/14 10:00 AM, Marcus Meissner wrote:
> >> Hi,
> >>
> >> This probably needs a CVE too, or does it have one?
> >>
> >> https://www.alertlogic.com/blog/dont-let-grinch-steal-christmas/
> >>
> http://www.pcworld.com/article/2860032/this-linux-grinch-could-put-a-hole-in-your-security-stocking.html
> >>
> >> Although it seems that the user is in the "wheel" group for this to be
> exploitable
> >> and is hard to specify what actions should be safed by another query or
> which should not.
> >>
> >> Ciao, Marcus
> >
> > Yeah I looked into this (the article/etc was completely confusing and
> > took some time to parse):
> >
> > 1) the article states they contacted red hat, we were unable to find
> > any inbound email or bugzilla entry pertaining to this issue, as always
> > if you have an issue you wish to report please contact
> secalert@...hat.com
> >
> > 2) this is expected behaviour, admin users can install software (do I
> > have to say this? really? yes. I was told I should say this).
> >
> > 3) don't run web apps as admin users (do I have to say this? really?
> > yes. I was told I should say this).
> >
> > 4) if you feel the need to run a web app as an admin user restrict what
> > they can do via SELinux, and don't let them install software (do I have
> > to say this? really? yes. I was told I should say this).
> >
> > So TL;DR: it's not a security vulnerability, and it will NOT be getting
> > a CVE.
> >
> > I can only assume this article/vuln is perhaps referring to something
> > like Cpanel and other control panels that people sometimes install
> > insecurely/improperly and then never update. Or something. Who knows.
> >
> > --
> > Kurt Seifried -- Red Hat -- Product Security -- Cloud
> > PGP A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993
> >
>
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