CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
NONE
Availability Impact
NONE
AV:N/AC:L/Au:N/C:P/I:N/A:N
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
NONE
Availability Impact
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
EPSS
Percentile
89.9%
IBM SECURITY ADVISORY
First Issued: Wed Oct 24 11:28:50 CDT 2018
The most recent version of this document is available here:
http://aix.software.ibm.com/aix/efixes/security/openssh_advisory12.asc
https://aix.software.ibm.com/aix/efixes/security/openssh_advisory12.asc
ftp://aix.software.ibm.com/aix/efixes/security/openssh_advisory12.asc
Security Bulletin: Vulnerability in OpenSSH affects AIX (CVE-2018-15473)
===============================================================================
SUMMARY:
Vulnerability in OpenSSH affects AIX.
===============================================================================
VULNERABILITY DETAILS:
CVEID: CVE-2018-15473
https://vulners.com/cve/CVE-2018-15473
https://vulners.com/cve/CVE-2018-15473
DESCRIPTION: OpenSSH could allow a remote attacker to obtain sensitive
information, caused by different responses to valid and invalid
authentication attempts. By sending a specially crafted request, an
attacker could exploit this vulnerability to enumerate valid usernames.
CVSS Base Score: 5.3
CVSS Temporal Score: See
https://exchange.xforce.ibmcloud.com/vulnerabilities/148397 for the
current score.
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N)
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 7.5.102.1500 key_w_fs
openssh.base.server 4.0.0.5200 7.5.102.1500 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_fix12.tar
http://aix.software.ibm.com/aix/efixes/security/openssh_fix12.tar
https://aix.software.ibm.com/aix/efixes/security/openssh_fix12.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 15473_fix.180919.epkg.Z openssh.base (7.5.102.1500 version) key_w_fix
VIOS Level Interim Fix (*.Z) Fileset Name (prereq for installation) KEY
---------------------------------------------------------------------------------------------
2.2.x 15473_fix.180919.epkg.Z openssh.base (7.5.102.1500 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_fix12.tar
cd openssh_fix12
Verify you have retrieved the fix intact:
The checksums below were generated using the
"openssl dgst -sha256 file" command is the following:
openssl dgst -sha256 filename KEY
-----------------------------------------------------------------------------------------------------
45ac81fc8766c41a7244ec2481ffa38aa90ca1b7c99b0b0acb1e4d82826b842a 15473_fix.180919.epkg.Z key_w_csum
Published advisory OpenSSH signature file location:
http://aix.software.ibm.com/aix/efixes/security/openssh_advisory12.asc.sig
https://aix.software.ibm.com/aix/efixes/security/openssh_advisory12.asc.sig
ftp://aix.software.ibm.com/aix/efixes/security/openssh_advisory12.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:
Note: Keywords labeled as KEY in this document are used for parsing
purposes.
If you would like to receive AIX Security Advisories via email,
please visit "My Notifications":
http://www.ibm.com/support/mynotifications
https://www.ibm.com/support/mynotifications
To view previously issued advisories, please visit:
http://www14.software.ibm.com/webapp/set2/subscriptions/onvdq
https://www14.software.ibm.com/webapp/set2/subscriptions/onvdq
Contact IBM Support for questions related to this announcement:
http://ibm.com/support/
https://ibm.com/support/
To obtain the OpenSSL public key that can be used to verify the
signed advisories and ifixes:
Download the key from our web page:
ftp://ftp.software.ibm.com/systems/power/AIX/systems_p_os_aix_security_pubkey.txt
Please contact your local IBM AIX support center for any
assistance.
REFERENCES:
Complete CVSS v3 Guide:
http://www.first.org/cvss/user-guide
https://www.first.org/cvss/user-guide
On-line Calculator v3:
http://www.first.org/cvss/calculator/3.0
https://www.first.org/cvss/calculator/3.0
RELATED INFORMATION:
Security Bulletin: Vulnerability in OpenSSH affects AIX (CVE-2018-15473)
https://www-01.ibm.com/support/docview.wss?uid=ibm10733751
ACKNOWLEDGEMENTS:
None
CHANGE HISTORY:
First Issued: Wed Oct 24 11:28:50 CDT 2018
===============================================================================
*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.
CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
NONE
Availability Impact
NONE
AV:N/AC:L/Au:N/C:P/I:N/A:N
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
NONE
Availability Impact
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
EPSS
Percentile
89.9%