Vulnerabilities in OpenSSH affect AIX.

IBM SECURITY ADVISORY

First Issued:Sun Feb 5 23:36:10 CST 2017

The most recent version of this document is available here:

http://aix.software.ibm.com/aix/efixes/security/openssh_advisory10.asc
https://aix.software.ibm.com/aix/efixes/security/openssh_advisory10.asc
ftp://aix.software.ibm.com/aix/efixes/security/openssh_advisory10.asc

Security Bulletin: Vulnerabilities in OpenSSH affect AIX (CVE-2016-8858,
CVE-2016-10009, CVE-2016-10011, CVE-2016-10012 )

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

SUMMARY:

Vulnerabilities in OpenSSH affect AIX.

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

VULNERABILITY DETAILS:

CVEID: CVE-2016-8858
DESCRIPTION:  OpenSSH is vulnerable to a denial of service, caused by an
error in the kex_input_kexinit() function. By sending specially crafted data
during the key exchange process, a remote attacker could exploit this
vulnerability to consume all available memory resources.
CVSS Base Score: 5.3
CVSS Temporal Score: See
    https://exchange.xforce.ibmcloud.com/vulnerabilities/118127 for the 
    current score.
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)

CVEID: CVE-2016-10009
DESCRIPTION: OpenSSH could allow a remote authenticated attacker to execute
 arbitrary code on the system, caused by the loading of a specially crafted
 PKCS#11 module across a forwarded agent channel. An attacker could exploit 
 this vulnerability to write files or execute arbitrary code on the system.
CVSS Base Score: 6.3
CVSS Temporal Score: See
    https://exchange.xforce.ibmcloud.com/vulnerabilities/119828 for the 
    current score.
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L)

CVEID: CVE-2016-10011
DESCRIPTION:OpenSSH could allow a local authenticated attacker to obtain
sensitive information, caused by a privilege separation flaw. An attacker 
could exploit this vulnerability to obtain host private key material and 
other sensitive information.
CVSS Base Score: 5.5
CVSS Temporal Score: See
    https://exchange.xforce.ibmcloud.com/vulnerabilities/119830 for the 
    current score.
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N)

CVEID: CVE-2016-10012
DESCRIPTION:OpenSSH could allow a local attacker to gain elevated privileges
on the system, caused by improper bounds checking in the shared memory
manager. An attacker could exploit this vulnerability to gain elevated 
privileges on the system.
CVSS Base Score: 5.9
CVSS Temporal Score: See
    https://exchange.xforce.ibmcloud.com/vulnerabilities/119831 for the 
    current score.
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L)


AFFECTED PRODUCTS AND VERSION:

    AIX 5.3, 6.1, 7.1, 7.2
    VIOS 2.2.x
    
    The following fileset levels are vulnerable:
    
    key_fileset = osrcaix
    
    Fileset                 Lower Level   Upper Level    KEY
    -------------------------------------------------------------
    openssh.base.client     4.0.0.5200    6.0.0.6203     key_w_fs
    openssh.base.server     4.0.0.5200    6.0.0.6203     key_w_fs

    Note:  To determine if your system is vulnerable, execute the
    following commands:

        lslpp -L | grep -i openssh.base.client
        lslpp -L | grep -i 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_fix10.tar
http://aix.software.ibm.com/aix/efixes/security/openssh_fix10.tar
https://aix.software.ibm.com/aix/efixes/security/openssh_fix10.tar

The links above are to a tar file containing this signed advisory, interim
fixes, and OpenSSL signatures for each interim fix.
These 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)  KEY
    ---------------------------------------------------------------------------------------------
    5.3, 6.1, 7.1, 7.2  6203_ifix.170124.epkg.Z  openssh.base(6.0.0.6203 version)       key_w_fix

    VIOS Level     Interim Fix (*.Z)             Fileset Name(prereq for installation)  KEY
    ---------------------------------------------------------------------------------------------
    2.2.*          6203_ifix.170124.epkg.Z       openssh.base(6.0.0.6203 version)       key_w_fix


Latest level of OpenSSH fileset is available from the web download site:
https://www14.software.ibm.com/webapp/iwm/web/reg/download.do?source=aixbp&lang=en_US&S_PKG=openssh&cp=UTF-8

       
To extract the fix from the tar file:

tar xvf openssh_fix10.tar
cd openssh_fix10

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                 KEY
    -----------------------------------------------------------------------------------------------------
    771b1ce548ed725aae3e6b58960d62bfba6b4d77f48ed4b01b1bb1d6acece770  6203_ifix.170124.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 of the fixes. If the sums or signatures cannot be confirmed,
contact IBM AIX Security at [email protected] and describe
the discrepancy.
        
Published advisory OpenSSL signature file location:

    http://aix.software.ibm.com/aix/efixes/security/openssh_advisory10.asc.sig
    https://aix.software.ibm.com/aix/efixes/security/openssh_advisory10.asc.sig
    ftp://aix.software.ibm.com/aix/efixes/security/openssh_advisory10.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

    After applying fix, IBM recommends that you regenerate your SSH keys as
    a precaution. 

    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:

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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:

    [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

X-Force Vulnerability Database: https://exchange.xforce.ibmcloud.com/vulnerabilities/118127
X-Force Vulnerability Database: https://exchange.xforce.ibmcloud.com/vulnerabilities/119828
X-Force Vulnerability Database: https://exchange.xforce.ibmcloud.com/vulnerabilities/119830
X-Force Vulnerability Database: https://exchange.xforce.ibmcloud.com/vulnerabilities/119831
CVE-2016-8858 : https://vulners.com/cve/CVE-2016-8858
CVE-2016-10009: https://vulners.com/cve/CVE-2016-10009
CVE-2016-10011: https://vulners.com/cve/CVE-2016-10011
CVE-2016-10012: https://vulners.com/cve/CVE-2016-10012

ACKNOWLEDGEMENTS:

None

CHANGE HISTORY:

First Issued: Sun Feb  5 23:36:10 CST 2017

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

*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.