The host_reliable_addrinfo function in support/export/hostname.c in nfs-utils before 1.2.4 does not properly use DNS to verify access to NFS exports, which allows remote attackers to mount filesystems by establishing crafted DNS A and PTR records.

The remote Oracle Linux 6 host has a package installed that is affected by multiple vulnerabilities as referenced in the ELSA-2011-1534 advisory.

    [1.2.3-15]
    - mout.nfs: Don't roll back to IPv4 whe IPv6 fails (bz 744657)
    - rpcdebug: Added pNFS and FSCache debugging (bz 747400)

    [1.2.3-14]
    - mount.nfs: Backported how upstream handles the SIGXFSZ signal (bz 697981)

    [1.2.3-13]
    - mount.nfs: Reworked the code that deals with RLIMIT_FSIZE (bz 697981)

    [1.2.3-12]
    - Removed the stripping of debugging information from rpcdebug (bz 729001)

    [1.2.3-11]
    - mount.nfs: Fixed problem in mount error verbosity patch (bz 731693)

    [1.2.3-10]
    - mount.nfs: add error verbosity to invalid versions (bz 731693)

    [1.2.3-9]
    - umount.nfs: Got IPV6 unmounts working again (bz 732673)
    - mountd: return multiple hosts exporting the same directory (bz 726112)
    - mount: Better error message for invalid version (bz 723780)

    [1.2.3-8]
    - initscripts: just try to mount rpc_pipefs always (bz 692702)
    - Rely on crypto module autoloading in init scripts
    - svcgssd: Document '-n' for svcgssd (bz 697359)
    - mount.nfs: anticipate RLIMIT_FSIZE (bz 697981)
    - exportfs manpage: Ipv6 update (bz 715078)
    - mountd: Stop segfault in mtab code (bz 723438)
    - exportfs: wilcards in exports can lead to unintended mounts (bz 715391)
    - umount: allow spaces in unmount paths (bz 702273)
    - specfile: reordered how libgssglue is linked in (bz 720479)

Tenable has extracted the preceding description block directly from the Oracle Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

This update fixes the following security issues :

When using wildcards in /etc/exports an attacker could gain unauthorized access to an nfs exported filesystem by creating a DNS record that resolves to the attacker's IP as well as to a trusted IP (CVE-2011-2500).

mount.nfs could corrupt /etc/mtab (CVE-2011-1749).

The nfs-utils packages provide a daemon for the kernel Network File System (NFS) server, and related tools such as the mount.nfs, umount.nfs, and showmount programs.

A flaw was found in the way nfs-utils performed IP based authentication of mount requests. In configurations where a directory was exported to a group of systems using a DNS wildcard or NIS (Network Information Service) netgroup, an attacker could possibly gain access to other directories exported to a specific host or subnet, bypassing intended access restrictions. (CVE-2011-2500)

It was found that the mount.nfs tool did not handle certain errors correctly when updating the mtab (mounted file systems table) file. A local attacker could use this flaw to corrupt the mtab file.
(CVE-2011-1749)

This update also fixes several bugs and adds an enhancement.

Users of nfs-utils are advised to upgrade to these updated packages, which contain backported patches to resolve these issues and add this enhancement. After installing this update, the nfs service will be restarted automatically.

Updated nfs-utils packages that fix two security issues, various bugs, and add one enhancement are now available for Red Hat Enterprise Linux 6.

The Red Hat Security Response Team has rated this update as having low security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

The nfs-utils packages provide a daemon for the kernel Network File System (NFS) server, and related tools such as the mount.nfs, umount.nfs, and showmount programs.

A flaw was found in the way nfs-utils performed IP based authentication of mount requests. In configurations where a directory was exported to a group of systems using a DNS wildcard or NIS (Network Information Service) netgroup, an attacker could possibly gain access to other directories exported to a specific host or subnet, bypassing intended access restrictions. (CVE-2011-2500)

It was found that the mount.nfs tool did not handle certain errors correctly when updating the mtab (mounted file systems table) file. A local attacker could use this flaw to corrupt the mtab file.
(CVE-2011-1749)

This update also fixes several bugs and adds an enhancement.
Documentation for these bug fixes and the enhancement will be available shortly from the Technical Notes document, linked to in the References section.

Users of nfs-utils are advised to upgrade to these updated packages, which contain backported patches to resolve these issues and add this enhancement. After installing this update, the nfs service will be restarted automatically.

When using wildcards in /etc/exports an attacker could gain unauthorized access to an NFS exported filesystem by creating a DNS record that resolves to the attacker's IP as well as to a trusted IP.
(CVE-2011-2500)

- Updated to latest upstream release: 1.2.4

    - Fixes CVE-2011-2500 (bz 716950)

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

ID	Name	Product	Family	Severity
181094	Oracle Linux 6 : nfs-utils (ELSA-2011-1534)	Nessus	Oracle Linux Local Security Checks	critical
75978	openSUSE Security Update : nfs-client (openSUSE-SU-2011:0747-1)	Nessus	SuSE Local Security Checks	high
61193	Scientific Linux Security Update : nfs-utils on SL6.x i386/x86_64	Nessus	Scientific Linux Local Security Checks	high
57015	RHEL 6 : nfs-utils (RHSA-2011:1534)	Nessus	Red Hat Local Security Checks	high
55548	SuSE 11.1 Security Update : NFS (SAT Patch Number 4821)	Nessus	SuSE Local Security Checks	high
55528	Fedora 15 : nfs-utils-1.2.4-0.fc15 (2011-8934)	Nessus	Fedora Local Security Checks	high

Detections

Analytics

CVE-2011-2500

critical

Tenable Plugins

critical

high

high

high

high

high