Date: Fri, 1 Oct 2010 16:02:04 -0600 From: Vincent Danen <vdanen@...hat.com> To: oss-security@...ts.openwall.com 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? >> >> http://git.altlinux.org/people/ldv/packages/?p=pam.git;a=commitdiff;h=06f882f30092a39a1db867c9744b2ca8d60e4ad6 >> >> 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
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