[ GLSA 200404-21 ] Multiple Vulnerabilities in Samba

From: Joshua J. Berry (condordes_at_gentoo.org)
Date: 04/29/04

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    To: gentoo-announce@gentoo.org
Date: Thu, 29 Apr 2004 13:25:03 -0700

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    Gentoo Linux Security Advisory GLSA 200404-21
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                                                http://security.gentoo.org/
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      Severity: Normal
         Title: Multiple Vulnerabilities in Samba
          Date: April 29, 2004
          Bugs: #41800, #45965
            ID: 200404-21

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    Synopsis
    ========

    There is a bug in smbfs which may allow local users to gain root via a
    setuid file on a mounted Samba share. Also, there is a tmpfile symlink
    vulnerability in the smbprint script distributed with Samba.

    Background
    ==========

    Samba is a package which allows UNIX systems to act as file servers for
    Windows computers. It also allows UNIX systems to mount shares exported
    by a Samba/CIFS/Windows server. smbmount is a program in the Samba
    package which allows normal users on a UNIX system to mount remote
    shares. smbprint is an example script included in the Samba package
    which can be used to facilitate network printing.

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

        -------------------------------------------------------------------
         Package / Vulnerable / Unaffected
        -------------------------------------------------------------------
      1 net-fs/samba <= 3.0.2a >= 3.0.2a-r2

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

    Two vulnerabilities have been discovered in Samba. The first
    vulnerability allows a local user who has access to the smbmount
    command to gain root. An attacker could place a setuid-root binary on a
    Samba share/server he or she controls, and then use the smbmount
    command to mount the share on the target UNIX box. The remote Samba
    server must support UNIX extensions for this to work. This has been
    fixed in version 3.0.2a.

    The second vulnerability is in the smbprint script. By creating a
    symlink from /tmp/smbprint.log, an attacker could cause the smbprint
    script to write to an arbitrary file on the system. This has been fixed
    in version 3.0.2a-r2.

    Impact
    ======

    Local users with access to the smbmount command may gain root access.
    Also, arbitrary files may be overwritten using the smbprint script.

    Workaround
    ==========

    To workaround the setuid bug, remove the setuid bits from the
    /usr/bin/smbmnt, /usr/bin/smbumount and /usr/bin/mount.cifs binaries.
    However, please note that this workaround will prevent ordinary users
    from mounting remote SMB and CIFS shares.

    To work around the smbprint vulnerability, set "debug=no" in the
    smbprint configuration.

    Resolution
    ==========

    All users should update to the latest version of the Samba package.

    The following commands will perform the upgrade:

        # emerge sync

        # emerge -pv ">=net-fs/samba-3.0.2a-r2"
        # emerge ">=net-fs/samba-3.0.2a-r2"

    Those who are using Samba's password database also need to run the
    following command:

        # pdbedit --force-initialized-passwords

    Those using LDAP for Samba passwords also need to check the
    sambaPwdLastSet attribute on each account, and ensure it is not 0.

    References
    ==========

      [ 1 ] BugTraq Thread: Samba 3.x + kernel 2.6.x local root vulnerability
            http://www.securityfocus.com/archive/1/353222/2004-04-09/2004-04-15/1
      [ 2 ] BugTraq: smbprint Vulnerability
            http://seclists.org/lists/bugtraq/2004/Mar/0189.html

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

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

         http://security.gentoo.org/glsa/glsa-200404-21.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 2004 Gentoo Technologies, 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/1.0

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