Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Fri, 1 Oct 2010 16:02:04 -0600
From: Vincent Danen <>
Subject: Re: Minor security flaw with pam_xauth

* [2010-09-28 00:17:29 +0400] Solar Designer wrote:

>On Mon, Sep 27, 2010 at 11:36:13AM -0600, Vincent Danen wrote:
>> * [2010-09-24 20:48:23 +0400] Solar Designer wrote:
>> >pam_env and pam_mail accessing the target user's files as root (and thus
>> >susceptible to attacks by the user) in Linux-PAM below 1.1.2, partially
>> >fixed in 1.1.2 - no CVE ID mentioned yet
>> >
>> >pam_env and pam_mail in Linux-PAM 1.1.2 not switching fsgid (or egid)
>> >and groups when accessing the target user's files (and thus potentially
>> >susceptible to attacks by the user) - CVE-2010-3430
>> >
>> >pam_env and pam_mail in Linux-PAM 1.1.2 not checking whether the
>> >setfsuid() calls succeed (no known impact with current Linux kernels,
>> >but poor practice in general) - CVE-2010-3431
>> These that are partially fixed are fixed in that git commit you noted
>> previously?
>> Or are they fixed in different commits?  It looks like they should all
>> be fixed in that commit, but I want to double-check.
>No, they are not fully fixed at all.  We're working on a patch (so you
>don't need to).  The commit has the mentioned partial fixes only.

Oh, ok.  Gotchya.

>> Are there patches available to fully fix these issues?  And are there
>> patches for 3430 and 3431 yet?
>This is the same question asked different ways.  We have a patch that
>we're reviewing internally.  To be made available soon.

Great, looking forward to seeing them.

>> I'm assuming also that those issues have
>> always existed although you say 'in 1.1.2', but they would affect
>> earlier versions yet, right?
>The original pam_env and pam_mail issues, yes.  The partial fixes, no,
>because there were no fixes at all before 1.1.2.

Ok, that makes sense.  I wasn't clear on the "partial fix" part.

>> Thanks for any clarification.  I'm trying to wrap my head around this
>> and the impact of these issues.  They all strike me as relatively minor
>> issues, but it is possible that I am missing or misunderstanding
>> something here.
>They're relatively minor because these modules are normally not used.
>However, if the modules are used in a PAM stack on a given install, then
>the original issues reported against pam_env and pam_mail by Sebastian
>become major ones.
>Additionally, as mentioned by Sebastian, pam_env's intended behavior is
>a security risk (user-provided env vars may affect some services in ways
>not expected by the sysadmin).  I am not sure how to deal with that.
>Maybe improve the documentation.

I'm not sure either, but I think that improving the documentation would
be a good start -- especially if that is pam_env's intended behaviour.

Vincent Danen / Red Hat Security Response Team 

Powered by blists - more mailing lists

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.