[Full-disclosure] [ GLSA 200509-15 ] util-linux: umount command validation error

From: Thierry Carrez (koon_at_gentoo.org)
Date: 09/20/05

  • Next message: Steve Smith: "Re: [Full-disclosure] Re: Cisco IOS hacked?" 
    Date: Tue, 20 Sep 2005 16:16:54 +0200
To: gentoo-announce@lists.gentoo.org

    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Gentoo Linux Security Advisory GLSA 200509-15
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
                                                http://security.gentoo.org/
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

      Severity: High
         Title: util-linux: umount command validation error
          Date: September 20, 2005
          Bugs: #105805
            ID: 200509-15

    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    Synopsis
    ========

    A command validation error in umount can lead to an escalation of
    privileges.

    Background
    ==========

    util-linux is a suite of useful Linux programs including umount, a
    program used to unmount filesystems.

    Affected packages
    =================

        -------------------------------------------------------------------
         Package / Vulnerable / Unaffected
        -------------------------------------------------------------------
      1 sys-apps/util-linux < 2.12q-r3 >= 2.12q-r3

    Description
    ===========

    When a regular user mounts a filesystem, they are subject to
    restrictions in the /etc/fstab configuration file. David Watson
    discovered that when unmounting a filesystem with the '-r' option, the
    read-only bit is set, while other bits, such as nosuid or nodev, are
    not set, even if they were previously.

    Impact
    ======

    An unprivileged user facing nosuid or nodev restrictions can umount -r
    a filesystem clearing those bits, allowing applications to be executed
    suid, or have device nodes interpreted. In the case where the user can
    freely modify the contents of the filesystem, privilege escalation may
    occur as a custom program may execute with suid permissions.

    Workaround
    ==========

    Two workarounds exist, first, the suid bit can be removed from the
    umount utility, or users can be restricted from mounting and unmounting
    filesystems in /etc/fstab.

    Resolution
    ==========

    All util-linux users should upgrade to the latest version:

        # emerge --sync
        # emerge --ask --oneshot --verbose ">=sys-apps/util-linux-2.12q-r3"

    References
    ==========

      [ 1 ] CAN-2005-2876
            http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=2005-2876

    Availability
    ============

    This GLSA and any updates to it are available for viewing at
    the Gentoo Security Website:

      http://security.gentoo.org/glsa/glsa-200509-15.xml

    Concerns?
    =========

    Security is a primary focus of Gentoo Linux and ensuring the
    confidentiality and security of our users machines is of utmost
    importance to us. Any security concerns should be addressed to
    security@gentoo.org or alternatively, you may file a bug at
    http://bugs.gentoo.org.

    License
    =======

    Copyright 2005 Gentoo Foundation, Inc; referenced text
    belongs to its owner(s).

    The contents of this document are licensed under the
    Creative Commons - Attribution / Share Alike license.

    http://creativecommons.org/licenses/by-sa/2.0

    _______________________________________________
    Full-Disclosure - We believe in it.
    Charter: http://lists.grok.org.uk/full-disclosure-charter.html
    Hosted and sponsored by Secunia - http://secunia.com/

  • Next message: Steve Smith: "Re: [Full-disclosure] Re: Cisco IOS hacked?"

    Relevant Pages
    • Quantcast