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Date: Wed, 17 Dec 2014 12:27:30 -0500
From: Daniel Kahn Gillmor <dkg@...thhorseman.net>
To: oss-security@...ts.openwall.com
Subject: Re: What is the "Grinch" polkit/wheel group issue?
On 12/17/2014 12:00 PM, Marcus Meissner wrote:
> 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.
from your first link:
>> Wheel is a special user group that controls access to the su command,
>> which allows a user to masquerade as another user. When a Linux system
>> is built, the default user is assigned to the wheel group that allows
>> for administrative task execution within the system. For example, if
>> the file is owned by user XYZ and group wheel, it will run as
>> XYZ:wheel, no matter who executes the file.
This paragraph suggests so many things which are simply wrong, confused,
or irrelevant that i don't know what to make of the rest of the article.
* modern debian GNU/Linux systems do not have a wheel group at all. No
particular versions or flavors of "Linux system"
* on systems where members of group wheel really do have unrestricted
access to the su command, having wheel in the first place *is* the
vulnerability -- it is a misconfiguration to expect an account to be
non-privileged if it is a member of wheel.
* the last sentence appears to be about setuid/setgid binaries, but
makes no mention that the overwhelming majority of binaries are not
setuid/setgid.
Later on, the post suggests that wheel group membership is related to
sudo privileges.
It also seems to assume that polkit always permits access for members of
group wheel. I can find no such configuration on a modern debian system.
I don't think there's anything significant in this ambiguous,
underspecified, and confused report.
--dkg
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