Operating System:

[AIX]

Published:

27 July 2007

Protect yourself against future threats.

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===========================================================================
             AUSCERT External Security Bulletin Redistribution

                          ESB-2007.0570 -- [AIX]
            AIX pioout Arbitrary Library Loading Vulnerability
                               27 July 2007

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:              pioout(4)
Publisher:            IBM
Operating System:     AIX 5.2, 5.3
Impact:               Root Compromise
Access:               Existing Account
CVE Names:            CVE-2007-4003

Original Bulletin:    
  http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=569

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IBM SECURITY ADVISORY

First Issued: Thu Jul 19 16:51:01 CDT 2007
===============================================================================
                           VULNERABILITY SUMMARY

VULNERABILITY:   AIX pioout Arbitrary Library Loading Vulnerability

PLATFORMS:       AIX 5.2, 5.3

SOLUTION:        Apply the APAR, interim fix or workaround as described
                 below.

THREAT:          An attacker may run arbitrary code with root privileges.

CERT VU Number:  n/a
CVE Number:      n/a
===============================================================================
                           DETAILED INFORMATION

I. OVERVIEW

    The pioout command is at the end of pipelines invoked by the piobe command
    (the print job manager) to print a file or a burst page on a printer.

II. DESCRIPTION

    An arbitrary library loading vulnerability exists within the pioout command
    which allows a non-privileged user to execute arbitrary code with super-
    user privileges.  This vulnerability is the result of pioout being setuid
    and world executable.

III. IMPACT

    Successful exploitation of this vulnerability will allow a local user to
    run arbitrary code with root privileges.

IV. PLATFORM VULNERABILITY ASSESSMENT

    To determine if your system is vulnerable, run the following command:

    # lslpp -l | grep printers.rte

    The following filesets are vulnerable:

    AIX Level           Lower Level       Upper Level
    -------------------------------------------------
    5.2.0               5.2.0.75          5.2.0.105
    5.3.0               5.3.0.30          5.3.0.60

V. SOLUTIONS

    A. APARS

        IBM provides the following fixes:

        AIX Level           APAR number       Availability
        --------------------------------------------------------------------
        5.2.0               IZ01121           10/31/2007 (subject to change)
        5.3.0               IZ01122           08/08/2007 (subject to change)

        AIX Version 5 APARs can be downloaded from:

        http://www.ibm.com/servers/eserver/support/unixservers/aixfixes.html

        NOTE: Affected customers are urged to upgrade to the latest applicable
        Technology Level and Service Pack.

    B. INTERIM FIXES

        Interim fixes are available.  The interim fix can be downloaded via
        ftp from:

        ftp://aix.software.ibm.com/aix/efixes/security/pioout_ifix.tar.Z

        This is a compressed tarball containing this advisory, interim fix
        packages and PGP signatures for each package.  The interim fixes below
        include prerequisite checking. This will enforce the correct mapping
        between the fixes and AIX Technology Levels.

        AIX Release & Technology Level         Interim fix
        ---------------------------------------------------------------
        5200-08                                IZ01121_08.070719.epkg.Z
        5200-09                                IZ01121_09.070719.epkg.Z
        5200-10                                IZ01121_10.070719.epkg.Z
        5300-04                                IZ01122_04.070719.epkg.Z
        5300-05                                IZ01122_05.070719.epkg.Z
        5300-06                                IZ01122_06.070719.epkg.Z

        IMPORTANT: If possible, it is recommended that a mksysb backup of the
        system be created.  Verify it is both bootable and readable before
        proceeding.

        These interim fixes have not been fully regression tested; thus, IBM
        does not warrant the fully correct functionality of the interim fix.
        Customers install the interim fix and operate the modified version of
        AIX at their own risk.

        Verify you have retrieved the fixes intact:

        The interim fixes below are named by using the technology level
        corresponding to the release that the fix applies to. The checksums
        below were generated using the "sum" and "md5sum" commands and are as
        follows:

        Filename                   sum        md5sum
        ----------------------------------------------------------------------
        IZ01121_08.070710.epkg.Z   50647 45   a821b7be0890066ebb7e08370c2431bb
        IZ01121_09.070710.epkg.Z   15247 45   e38cb8dcd2e46b2a0d260beac059f075
        IZ01121_10.070710.epkg.Z   43854 45   fe45e6967d616b829b26452def22dd20
        IZ01122_04.070710.epkg.Z   14449 45   3da46671ac956c0ec341da0f6ea56ea6
        IZ01122_05.070710.epkg.Z   10193 45   878460aa65e0446d692e6d9585475c9a
        IZ01122_06.070710.epkg.Z   29050 46   3f14967bcb2deeb3fc9a34fbd21ea52d

        These sums should match exactly. The PGP signatures in the
        compressed tarball and on this advisory can also be used to verify
        the integrity of the various files they correspond to.  If the sums
        or signatures cannot be confirmed, double check the command results
        and the download site address.  If those are OK, contact IBM AIX
        Security at security-alert@austin.ibm.com and describe the
        discrepancy.

    C. INTERIM FIX INSTALLATION

        These packages use the new Interim Fix Management Solution to install
        and manage interim fixes.  More information can be found at:

        http://www14.software.ibm.com/webapp/set2/sas/f/aix.efixmgmt/home.html

        To preview an epkg interim fix installation execute the following
        command:

        # emgr -e ipkg_name -p       # where ipkg_name is the name of the
                                     # interim fix package being previewed.

        To install an epkg interim fix package, execute the following command:

        # emgr -e ipkg_name -X       # where ipkg_name is the name of the
                                     # interim fix package being installed.

        The "X" flag will expand any filesystems if required.

VI. WORKAROUNDS

    A. OPTION 1

        In most cases the pioout command will only be run by a privileged user
        and can have its permissions altered with the following command:

        # chmod 500 /usr/lib/lpd/pio/etc/pioout

        NOTE: This will affect users of the printq group attempting to run this
        command.

    B. OPTION 2

        Customers running AIX 5.3.0 TL06 may install the bos.rte.security
        fileset and take advantage of the 'fpm' command to disable the setuid
        capabilities of pioout.  The pioout command is part of the 'high' level
        database.

VII. OBTAINING FIXES

    AIX Version 5 APARs can be downloaded from:

        http://www.ibm.com/servers/eserver/support/unixservers/aixfixes.html

    Security related Interim Fixes can be downloaded from:

        ftp://aix.software.ibm.com/aix/efixes/security

VII. CONTACT INFORMATION

    If you would like to receive AIX Security Advisories via email, please
    visit:

        http://www14.software.ibm.com/webapp/set2/subscriptions/pqvcmjd

    Comments regarding the content of this announcement can be directed to:

        security-alert@austin.ibm.com

    To request the PGP public key that can be used to communicate
    securely with the AIX Security Team send email to
    security-alert@austin.ibm.com with a subject of "get key". The key
    can also be downloaded from a PGP Public Key Server. The key id is
    0x4265D862.

    Please contact your local IBM AIX support center for any assistance.

    eServer is a trademark of International Business Machines Corporation.
    IBM, AIX and pSeries are registered trademarks of International Business
    Machines Corporation.  All other trademarks are property of their
    respective holders.

VIII. ACKNOWLEDGMENTS

    iDefense (http://labs.idefense.com/) credits an anonymous contributer.
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