Vulnerability in NTPv4 affects AIX

IBM SECURITY ADVISORY

First Issued: Mon Feb 22 08:06:13 CST 2016

The most recent version of this document is available here:

http://aix.software.ibm.com/aix/efixes/security/ntp_advisory5.asc
https://aix.software.ibm.com/aix/efixes/security/ntp_advisory5.asc
ftp://aix.software.ibm.com/aix/efixes/security/ntp_advisory5.asc

Security Bulletin: Vulnerability in NTPv4 affects AIX (CVE-2015-5300)

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

SUMMARY:

There is a vulnerability in NTPv4 that impacts AIX.

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

VULNERABILITY DETAILS:

CVEID: CVE-2015-5300
DESCRIPTION: Network Time Protocol (NTP) could allow a remote attacker to
    bypass security restrictions, caused by the failure to correctly
    implement the threshold limitation for the '-g' option. An attacker
    could exploit this vulnerability using man-in-the-middle techniques to
    intercept NTP traffic and make multiple steps larger than the panic
    threshold. 
CVSS Base Score: 4.3 
CVSS Temporal Score: See
    https://exchange.xforce.ibmcloud.com/vulnerabilities/107594 for more
    information.
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N)


AFFECTED PRODUCTS AND VERSIONS:

    AIX 6.1, 7.1, 7.2
    VIOS 2.2.x

    The following fileset levels are vulnerable:
    
    key_fileset = aix

    Fileset             Lower Level  Upper Level KEY 
    -----------------------------------------------------
    ntp.rte             6.1.6.0      6.1.6.4     key_w_fs
    ntp.rte             7.1.0.0      7.1.0.4     key_w_fs
    
    Note:  to find out whether the affected filesets are installed 
    on your systems, refer to the lslpp command found in AIX user's guide.

    Example:  lslpp -L | grep -i ntp.rte 

REMEDIATION:

    A. APARS
        
        IBM has assigned the following APARs to this problem:

        AIX Level APAR     Availability  SP   KEY
        ------------------------------------------------
        6.1.9     IV81129  5/20/16       SP7  key_w_apar
        7.1.3     IV81130  9/1/16        SP7  key_w_apar
        7.1.4     IV81130  5/20/16       SP2  key_w_apar
        7.2.0     IV81130  5/20/16       SP2  key_w_apar 

        Subscribe to the APARs here:

        http://www.ibm.com/support/docview.wss?uid=isg1IV81129
        http://www.ibm.com/support/docview.wss?uid=isg1IV81130

        By subscribing, you will receive periodic email alerting you
        to the status of the APAR, and a link to download the fix once
        it becomes available.

    B. FIXES

        Fixes are available.

        The fixes can be downloaded via ftp or http from:

        ftp://aix.software.ibm.com/aix/efixes/security/ntp_fix5.tar
        http://aix.software.ibm.com/aix/efixes/security/ntp_fix5.tar
        https://aix.software.ibm.com/aix/efixes/security/ntp_fix5.tar 

        The link above is to a tar file containing this signed
        advisory, fix packages, and OpenSSL signatures for each package.
        The fixes below include prerequisite checking. This will
        enforce the correct mapping between the fixes and AIX
        Technology Levels.

        
        AIX Level  Interim Fix (*.Z)         KEY
        ----------------------------------------------
        6.1.x      IV81129m6a.160204.epkg.Z  key_w_fix
        7.1.x      IV81130m5a.160204.epkg.Z  key_w_fix
        7.2.x      IV81130m5a.160204.epkg.Z  key_w_fix
        
        VIOS Level  Interim Fix (*.Z)         KEY
        -----------------------------------------------
        2.2.x       IV81129m6a.160204.epkg.Z  key_w_fix
        

        To extract the fixes from the tar file:

        tar xvf ntp_fix5.tar
        cd ntp_fix5

        Verify you have retrieved the fixes intact:

        The checksums below were generated using the
        "openssl dgst -sha256 file" command as the followng:

        openssl dgst -sha256                                              filename                 KEY
        -----------------------------------------------------------------------------------------------------
        49b5b7d12f2242c91c9132e44eecc8288c1a822e6601d7116a831586621a46ee  IV81129m6a.160204.epkg.Z key_w_csum
        042f4446acca218b1f5a7ce77413d8273593298eb5360cf21db5c86d923fe910  IV81130m5a.160204.epkg.Z key_w_csum

        These sums should match exactly. The OpenSSL signatures in the tar
        file and on this advisory can also be used to verify the
        integrity of the fixes.  If the sums or signatures cannot be
        confirmed, contact IBM AIX Security at
        [email protected] and describe the discrepancy.
        
        openssl dgst -sha1 -verify <pubkey_file> -signature <advisory_file>.sig <advisory_file>

        openssl dgst -sha1 -verify <pubkey_file> -signature <ifix_file>.sig <ifix_file>

        Published advisory OpenSSL signature file location:

        http://aix.software.ibm.com/aix/efixes/security/ntp_advisory5.asc.sig
        https://aix.software.ibm.com/aix/efixes/security/ntp_advisory5.asc.sig
        ftp://aix.software.ibm.com/aix/efixes/security/ntp_advisory5.asc.sig 

    C. FIX AND INTERIM FIX INSTALLATION

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

        To preview a fix installation:

        installp -a -d fix_name -p all  # where fix_name is the name of the
                                    # fix package being previewed.
        To install a fix package:

        installp -a -d fix_name -X all  # where fix_name is the name of the
                                    # fix package being installed.

        After installation the ntp daemon must be restarted:

        stopsrc -s xntpd

        startsrc -s xntpd

        Interim fixes have had limited functional and regression
        testing but not the full regression testing that takes place
        for Service Packs; however, IBM does fully support them.

        Interim fix management documentation can be found at:

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

        To preview an interim fix installation:

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

        To install an interim fix package:

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

WORKAROUNDS AND MITIGATIONS:

    None.

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

CONTACT US:

Note: Keywords labeled as KEY in this document are used for parsing
purposes.

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

    [email protected]

To obtain the OpenSSL public key that can be used to verify the
signed advisories and ifixes:

    Download the key from our web page:

http://www.ibm.com/systems/resources/systems_p_os_aix_security_pubkey.txt

To obtain the PGP public key that can be used to communicate
securely with the AIX Security Team via [email protected] you
can either:

    A. Download the key from our web page:

http://www.ibm.com/systems/resources/systems_p_os_aix_security_pgppubkey.txt

    B. Download the key from a PGP Public Key Server. The key ID is:

        0x28BFAA12

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

REFERENCES:

Complete CVSS v3 Guide:  http://www.first.org/cvss/user-guide
On-line Calculator v3:
    http://www.first.org/cvss/calculator/3.0

ACKNOWLEDGEMENTS:

None 

CHANGE HISTORY:

First Issued: Mon Feb 22 08:06:13 CST 2016

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

*The CVSS Environment Score is customer environment specific and will
ultimately impact the Overall CVSS Score. Customers can evaluate the impact
of this vulnerability in their environments by accessing the links in the
Reference section of this Security Bulletin.

Disclaimer
According to the Forum of Incident Response and Security Teams (FIRST), the
Common Vulnerability Scoring System (CVSS) is an “industry open standard
designed to convey vulnerability severity and help to determine urgency and
priority of response.” IBM PROVIDES THE CVSS SCORES “AS IS” WITHOUT WARRANTY
OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT
OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY.