Operating System:

[AIX]

Published:

22 October 2015

Protect yourself against future threats.

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

                               ESB-2015.2675
         Security Bulletin:  Vulnerabilities in OpenSSH affect AIX
                     (CVE-2015-6563 and CVE-2015-6564)
                              22 October 2015

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

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

Product:           OpenSSH
Publisher:         IBM
Operating System:  AIX
Impact/Access:     Provide Misleading Information -- Existing Account
                   Increased Privileges           -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2015-6564 CVE-2015-6563 

Reference:         ASB-2015.0090
                   ESB-2015.2655
                   ESB-2015.2442

Original Bulletin: 
   http://www14.software.ibm.com/webapp/set2/subscriptions/onvdq?mode=18&ID=4472&myns=pwraix53&mync=E&cm_sp=pwraix53-_-NULL-_-E

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

SUMMARY:

    Vulnerabilities in OpenSSH affect AIX
    
    
===============================================================================

VULNERABILITY DETAILS:

    CVEID: CVE-2015-6563
    DESCRIPTION: The monitor component in sshd accepts extraneous username 
        data in MONITOR_REQ_PAM_INIT_CTX requests, which allows local users to
        conduct impersonation attacks by leveraging any SSH login access in
        conjunction with control of the sshd uid to send a crafted
        MONITOR_REQ_PWNAM request.
    CVSS Base Score: 4
    CVSS Temporal Score: See
        https://exchange.xforce.ibmcloud.com/vulnerabilities/105881 for the
        current score.
    CVSS Environmental Score*: Undefined
    CVSS Vector: (AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N)
    
    
    CVEID: CVE-2015-6564
    DESCRIPTION: Use-after-free vulnerability in the mm_answer_pam_free_ctx 
        function in sshd might allow local users to gain privileges by
        leveraging control of the sshd uid to send an unexpectedly early
        MONITOR_REQ_PAM_FREE_CTX request.
    CVSS Base Score: 7.4
    CVSS Temporal Score: See
        https://exchange.xforce.ibmcloud.com/vulnerabilities/105882 for the
        current score.
    CVSS Environmental Score*: Undefined
    CVSS Vector: (AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H)


    AFFECTED PRODUCTS AND VERSIONS:
    
        AIX 5.3, 6.1, 7.1
        VIOS 2.2.x

        The following fileset levels are vulnerable:

        AIX Fileset             Lower Level   Upper Level    KEY
        -------------------------------------------------------------
        openssh.base.client     4.0.0.5200    6.0.0.6201     key_w_fs
        openssh.base.server     4.0.0.5200    6.0.0.6201     key_w_fs
        
        Note:  To determine if your system is vulnerable, execute the
        following commands:

            lslpp -L openssh.base.client
            lslpp -L openssh.base.server
            
        

    REMEDIATION:

        A. FIXES

            Fixes are available.  The fixes can be downloaded via ftp and
            http from:

            ftp://aix.software.ibm.com/aix/efixes/security/openssh_fix6.tar
            http://aix.software.ibm.com/aix/efixes/security/openssh_fix6.tar
            https://aix.software.ibm.com/aix/efixes/security/openssh_fix6.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
            releases.

	        Note that the tar file contains Interim fixes that are based on
            OpenSSH version as given below - 

            You must be on the 'prereq for installation' level before
            applying the interim fix. This may require installing a new
            level(prereq version) first.
            

            AIX Level      Interim Fix (*.Z)         
            Fileset Name(prereq for installation)
            -------------------------------------------
            --------------------------------------
            5.3, 6.1, 7.1  6110_ifix.151009.epkg.Z   
            openssh.base(6.0.0.6110 version)
            5.3, 6.1, 7.1  6201_ifix.151009.epkg.Z   
            openssh.base(6.0.0.6201 version)

            VIOS Level     Interim Fix (*.Z)	     
            Fileset Name(prereq for installation)
            -----------------------------------------------
            ----------------------------------
            2.2.*          6110_ifix.151009.epkg.Z   
            openssh.base(6.0.0.6110 version)
            2.2.*          6201_ifix.151009.epkg.Z   
            openssh.base(6.0.0.6201 version)


	        Note - OpenSSH releases 6.0.0.6110 and 6.0.0.6201 are same
            except that 6.0.0.6201 is compiled with OpenSSL v1.0.1 and
            contains ECDSA key support. Refer to the fileset readme file for
            more details.

            To extract the fix from the tar file:

            tar xvf openssh_fix6.tar
            cd openssh_fix6

            Verify you have retrieved the fix intact:

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

            openssl dgst -sha256                                              
            filename	 
            ----------------------------------------------------------
            -------------------------------
            fa701ce210c496b8692ed339b76a2204f969d156ede171a923125ec313fea3f2  
            6110_ifix.151009.epkg.Z
            3acd9aba41d2abde519bde08b17b8f2d306ba88392b6788b0fd051a85647a9a2  
            6201_ifix.151009.epkg.Z

        
            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 security-alert@austin.ibm.com and
            describe the discrepancy.
            
            Published advisory OpenSSL signature file location:

       
http://aix.software.ibm.com/aix/efixes/security/openssh_advisory6.asc.sig
       
https://aix.software.ibm.com/aix/efixes/security/openssh_advisory6.asc.sig
        ftp://aix.software.ibm.com/aix/efixes/security/openssh_advisory6.asc.sig
      

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

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

            
        B. 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.

            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:

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

        http://www.ibm.com/support/mynotifications

    To view previously issued advisories, please visit:

        http://www14.software.ibm.com/webapp/set2/subscriptions/onvdq
 
    Comments regarding the content of this announcement can be
    directed to:

        security-alert@austin.ibm.com

    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 security-alert@austin.ibm.com 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:

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

    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.

    Complete CVSS Guide: http://www.first.org/cvss/v2/guide
    On-line Calculator V2: https://nvd.nist.gov/CVSS-v2-Calculator

    X-Force Vulnerability Database:
        https://exchange.xforce.ibmcloud.com/vulnerabilities/105881
    X-Force Vulnerability Database:
        https://exchange.xforce.ibmcloud.com/vulnerabilities/105882
    CVE-2015-6563: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-6563
    CVE-2015-6564: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-6564
    
    
ACKNOWLEDGEMENTS:

    None. 


CHANGE HISTORY:

    First Issued: Wed Oct 21 09:17:40 CDT 2015 
    
    
======================================================

    *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 Flash.

    Note: 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.

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