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AUSCERT External Security Bulletin Redistribution
ESB-2021.1502
Security Bulletin: Vulnerabilities in OpenSSL affect AIX
(CVE-2021-23839, CVE-2021-23840, and CVE-2021-23841)
4 May 2021
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: PowerVM Virtual I/O Server
Publisher: IBM
Operating System: AIX
Impact/Access: Denial of Service -- Remote/Unauthenticated
Reduced Security -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2021-23841 CVE-2021-23840 CVE-2021-23839
Reference: ESB-2021.1015
ESB-2021.0897
ESB-2021.0636.2
Original Bulletin:
https://www.ibm.com/support/pages/node/6443405
- --------------------------BEGIN INCLUDED TEXT--------------------
Vulnerabilities in OpenSSL affect AIX (CVE-2021-23839, CVE-2021-23840, and
CVE-2021-23841)
Document Information
Document number : 6443405
Modified date : 03 May 2021
Product : PowerVM Virtual I/O Server
Software version : 3.1
Operating system(s): AIX
Summary
There are vulnerabilities in OpenSSL used by AIX.
Vulnerability Details
CVEID: CVE-2021-23839
DESCRIPTION: OpenSSL could provide weaker than expected security, caused by
incorrect SSLv2 rollback protection that allows for the inversion of the logic
during a padding check. If the server is configured for SSLv2 support at
compile time, configured for SSLv2 support at runtime or configured for SSLv2
ciphersuites, it will accept a connection if a version rollback attack has
occurred and erroneously reject a connection if a normal SSLv2 connection
attempt is made.
CVSS Base score: 5.9
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/
196849 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N)
CVEID: CVE-2021-23840
DESCRIPTION: OpenSSL is vulnerable to a denial of service, caused by an integer
overflow in CipherUpdate. By sending an overly long argument, an attacker could
exploit this vulnerability to cause the application to crash.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/
196848 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
CVEID: CVE-2021-23841
DESCRIPTION: OpenSSL is vulnerable to a denial of service, caused by a NULL
pointer dereference in the X509_issuer_and_serial_hash() function. By parsing
the issuer field, an attacker could exploit this vulnerability to cause the
application to crash.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/
196847 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Affected Products and Versions
+--------------------+----------+
|Affected Product(s) |Version(s)|
+--------------------+----------+
|AIX |7.1 |
+--------------------+----------+
|AIX |7.2 |
+--------------------+----------+
|VIOS |3.1 |
+--------------------+----------+
The following fileset levels are vulnerable:
+------------+--------------+--------------+
|Fileset |Lower Level |Upper Level |
+------------+--------------+--------------+
|openssl.base|1.0.2.500 |1.0.2.2100 |
+------------+--------------+--------------+
|openssl.base|20.13.102.1000|20.16.102.2100|
+------------+--------------+--------------+
Note:
A. 0.9.8, 1.0.1 OpenSSL versions are out-of-support. Customers are advised to
upgrade to currently supported OpenSSL 1.0.2 version.
B. Latest level of OpenSSL fileset is available from the web download site:
https://www-01.ibm.com/marketing/iwm/iwm/web/pickUrxNew.dosource=aixbp&S_PKG=
openssl
To find out whether the affected filesets are installed on your systems, refer
to the lslpp command found in the AIX user's guide.
Example: lslpp -L | grep -i openssl.base
Remediation/Fixes
A. FIXES
The fixes can be downloaded via ftp or http from:
ftp://aix.software.ibm.com/aix/efixes/security/openssl_fix33.tar
http://aix.software.ibm.com/aix/efixes/security/openssl_fix33.tar
https://aix.software.ibm.com/aix/efixes/security/openssl_fix33.tar
The links above are 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.
Note that the tar file contains Interim fixes that are based on OpenSSL
version, and AIX OpenSSL fixes are cumulative.
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 |Fileset Name (prereq for installation)|
+---------+-----------------------+--------------------------------------+
|7.1, 7.2 |1022100b.210323.epkg.Z |openssl.base (1.0.2.2100) |
+---------+-----------------------+--------------------------------------+
|7.1, 7.2 |fips2100b.210323.epkg.Z|openssl.base (20.16.102.2100) |
+---------+-----------------------+--------------------------------------+
+----------+-----------------------+--------------------------------------+
|VIOS Level|Interim Fix |Fileset Name (prereq for installation)|
+----------+-----------------------+--------------------------------------+
|3.1 |1022100b.210323.epkg.Z |openssl.base (1.0.2.2100) |
+----------+-----------------------+--------------------------------------+
|3.1 |fips2100b.210323.epkg.Z|openssl.base (20.16.102.2100) |
+----------+-----------------------+--------------------------------------+
To extract the fixes from the tar file:
tar xvf openssl_fix33.tar
cd openssl_fix33
Verify you have retrieved the fixes intact:
The checksums below were generated using the "openssl dgst -sha256 file"
command as the following:
+----------------------------------------------------------------+-----------------------+
|openssl dgst -sha256 |filename |
+----------------------------------------------------------------+-----------------------+
|6d2cf96d3d8d78af02f92071d50bffeae257dfc136d28ab15957e8e143105045|1022100b.210323.epkg.Z |
+----------------------------------------------------------------+-----------------------+
|6cfef2f6f82d2dfffd986383bcbfbbaa6041625165ab15028318c956a9afaa53|fips2100b.210323.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 Support at https://
ibm.com/support/ 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/openssl_advisory33.asc.sig
https://aix.software.ibm.com/aix/efixes/security/openssl_advisory33.asc.sig
ftp://aix.software.ibm.com/aix/efixes/security/openssl_advisory33.asc.s...
B. FIX AND INTERIM FIX INSTALLATION
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
Change History
12 Apr 2021: Initial Publication
Document Location
Worldwide
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