A security flaw was found in the way nfs-utils performed authentication of an incoming request, when an IP based authentication mechanism was used and certain file systems were exported to either to a netgroup or a wildcard (e.g. *.my.domain), and some file systems (either the same or different to the first set) were exported to specific hosts, IP addresses, or a subnet. A remote attacker, able to create global DNS entries could use this flaw to access above listed, exported file systems. References: [1] https://bugzilla.novell.com/show_bug.cgi?id=701702 [2] http://www.openwall.com/lists/oss-security/2011/06/27/7 (CVE Request) Relevant upstream patch: [3] http://marc.info/?l=linux-nfs&m=130875695821953&w=2
Further details how to reproduce the issue (from [1]): ====================================================== 1/ On a server, export a filesystem to an IP address and a random wildcard. e.g. /export 192.168.1.1(rw,no_root_squash,no_subtree_check) *.mydomain.com(ro,no-subtree_check) exportfs -av 2/ In /etc/hosts define some name to have two IP address; one that was given in /etc/exports, one that is the IP address of your attach client 192.168.1.1 attacker 192.168.0.1 attacker 3/ try to mount /export from 192.168.0.1 This should normally fail, but the bug causes it to succeed.
This issue did NOT affect the versions of the nfs-utils package, as shipped with Red Hat Enterprise Linux 4 and 5. -- This issue affects the versions of the nfs-utils package, as shipped with Red Hat Enterprise Linux 6. -- This issue affects the versions of the nfs-utils package, as shipped with Fedora release of 14 and 15. Please schedule an update.
Created nfs-utils tracking bugs for this issue Affects: fedora-all [bug 716950]
The CVE identifier of CVE-2011-2500 has been assigned to this issue: http://www.openwall.com/lists/oss-security/2011/06/28/17
Statement: This issue did not affect the versions of nfs-utils as shipped with Red Hat Enterprise Linux 4 and 5. The Red Hat Security Response Team has rated this issue as having low security impact; a future update in Red Hat Enterprise Linux 6 may address this flaw.
This issue has been addressed in following products: Red Hat Enterprise Linux 6 Via RHSA-2011:1534 https://rhn.redhat.com/errata/RHSA-2011-1534.html