Bug 1101751 (CVE-2014-0249)

Summary: CVE-2014-0249 sssd: incorrect expansion of group membership when encountering a non-POSIX group
Product: [Other] Security Response Reporter: Vincent Danen <vdanen>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: abokovoy, fweimer, grajaiya, jgalipea, jhrozek, jkurik, lslebodn, mkosek, osoukup, pbrezina, redhat, sbose, sgallagh, ssorce
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: sssd 1.11.7 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2017-01-10 15:01:34 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 995389, 1101756, 1103487, 1103488    
Bug Blocks: 1101758    

Description Vincent Danen 2014-05-27 20:21:59 UTC
It was reported [1] that SSSD improperly expanded group membership when it encountered a non-POSIX group in the group membership chain.  For instance:

  user -> posix_group1 -> non_posix_group -> posix_group2

With the group memberships noted above, SSSD should include the user as a member of both posix_group1 and posix_group2, however due to the position of the non-POSIX group, SSSD halts processing at it and never reaches posix_group2, leaving the user as a member of posix_group1 and not posix_group2.

SSSD has the capability to set a 'deny' ACL for both users and groups, so in a situation like that illustrated above, if posix_group2 was present in a 'deny' ACL, the user would be granted access because they are not shown as having membership in the denied group.  This could grant unintended access to certain users in an environment where non-POSIX groups are used in addition to POSIX groups.

There is currently no patch to correct this issue.

[1] https://lists.fedorahosted.org/pipermail/sssd-devel/2014-May/019495.html

Comment 1 Vincent Danen 2014-05-27 20:22:25 UTC
Created sssd tracking bugs for this issue:

Affects: fedora-all [bug 1101756]

Comment 2 Huzaifa S. Sidhpurwala 2014-05-29 07:45:13 UTC

This issue affects the version of sssd package as shipped with Red Hat Enterprise Linux 5. The Red Hat Security Response Team has rated this issue as having Low security impact, a future update may address this flaw.

Comment 5 Tomas Hoger 2015-03-12 14:35:57 UTC
This issue was already fixed in sssd updates in Red Hat Enterprise Linux 6 (in 6.6, via RHBA-2014:1375) and Red Hat Enterprise Linux 7 (in 7.1, via RHBA-2015:0441).