Date: Wed, 12 Dec 2012 13:48:46 -0700 From: Vincent Danen <vdanen@...hat.com> To: oss-security@...ts.openwall.com Subject: CVE-2012-5617: gksu-polkit privileged code execution with unprivileged credentials This is a heads-up on a flaw reported to us regarding gksu-polkit. This was sent to the linux-distros@ mailing list last week. Miroslav Trmac of Red Hat reported that gksu-polkit ships with an extremely permissive PolicyKit policy configuration file. Because gksu-polkit allows a user to execute a program with administrative privileges, and because the default allow_active setting is "auth_self" rather than "auth_admin", any local user can use gksu-polkit to execute arbitrary programs (like a bash shell) with root privileges. For example: $ cat foo.sh #! /bin/bash id -a # not just gksu-polkit id -a because gksu-polkit tries to interpret the # -a # this prompts for user's password only $ gksu-polkit /home/user/foo.sh uid=0(root) gid=0(root) groups=0(root) context=system_u:system_r:initrc_t:s0 (As an aside, I did some peeking because there was some discussion as to whether or not this was intended behaviour. It does not seem as though gksu-polkit is _intended_ to grant root access to every local user, even though they need to actually be at the computer (I've not tested whether or not this can be exploited via a remote X session, but it's possible). Even if this is not remotely exploitable, we do tend to require administrator authentication by local users (via su) or an administrator to grant such privileges (via sudo), so to me this is definitely a flaw). References: http://anonscm.debian.org/gitweb/?p=users/kov/gksu-polkit.git;a=blob;f=data/org.gnome.gksu.policy;h=ff0e4187941147d4f6c7ca53ebd1757521337288;hb=HEAD https://bugzilla.redhat.com/show_bug.cgi?id=883162 -- Vincent Danen / Red Hat Security Response Team
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