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Security Bulletin: AIX is vulnerable to a denial of service due to libxml2 (CVE-2023-29469 and CVE-2023-28484)

Security Bulletin


Summary

Vulnerabilities in libxml2 could allow a remote attacker to cause a denial of service (CVE-2023-29469 and CVE-2023-28484). AIX uses libxml2 as part of its XML parsing functions.

Vulnerability Details

CVEID:   CVE-2023-29469
DESCRIPTION:   GNOME libxml2 is vulnerable to a denial of service, caused by a double free flaw in the xmlDictComputeFastKey function due to hashing empty strings are not null-terminated. By persuading a victim to open a specially crafted XML content, a remote attacker could exploit this vulnerability to cause a denial of service condition.
CVSS Base score: 5.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/253143 for the current score.
CVSS Vector: (CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H)

CVEID:   CVE-2023-28484
DESCRIPTION:   GNOME libxml2 is vulnerable to a denial of service, caused by a NULL pointer dereference flaw in the xmlSchemaFixupComplexType function. By persuading a victim to open a specially crafted XML content, a remote attacker could exploit this vulnerability to cause a denial of service condition.
CVSS Base score: 5.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/253138 for the current score.
CVSS Vector: (CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H)

Affected Products and Versions

Affected Product(s)Version(s)
AIX7.2
AIX7.3
VIOS3.1

 

The following fileset levels are vulnerable:

FilesetLower LevelUpper Level
bos.rte.control7.2.5.07.2.5.6
bos.rte.control7.2.5.1007.2.5.103
bos.rte.control7.2.5.2007.2.5.201
bos.rte.control7.3.0.07.3.0.3
bos.rte.control7.3.1.07.3.1.1

 

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 bos.rte.control

 

Remediation/Fixes

A. APARS

            

IBM has assigned the following APARs to this problem:

AIX LevelAPARSP
7.2.5IJ47597SP07
7.3.0IJ47629N/A
7.3.1IJ47630SP03

 

VIOS LevelAPARSP
3.1.2IJ47631N/A
3.1.3IJ476323.1.3.50
3.1.4IJ475973.1.4.30

 

Subscribe to the APARs here:

https://www.ibm.com/support/pages/apar/IJ47597

https://www.ibm.com/support/pages/apar/IJ47629

https://www.ibm.com/support/pages/apar/IJ47630

https://www.ibm.com/support/pages/apar/IJ47631

https://www.ibm.com/support/pages/apar/IJ47632

 

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

 

IBM strongly recommends addressing the vulnerability now.

 

AIX and VIOS fixes are available. The fixes are cumulative and address previously issued AIX/VIOS libxml2 security bulletins with respect to SP and TL:

https://aix.software.ibm.com/aix/efixes/security/libxml2_advisory4.asc

https://www.ibm.com/support/pages/node/6953825

https://aix.software.ibm.com/aix/efixes/security/libxml2_advisory3.asc

https://www.ibm.com/support/pages/node/6619729

 

 

The AIX and VIOS fixes can be downloaded via ftp or http from:

https://aix.software.ibm.com/aix/efixes/security/libxml2_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 LevelInterim Fix
7.2.5.4IJ47597m4a.230718.epkg.Z
7.2.5.5IJ47597m6a.230717.epkg.Z
7.2.5.6IJ47597m6a.230717.epkg.Z
7.3.0.2IJ47629m4a.230718.epkg.Z
7.3.0.3IJ47629m4a.230718.epkg.Z
7.3.0.4IJ47629m4a.230718.epkg.Z
7.3.1.1IJ47630m2a.230718.epkg.Z
7.3.1.2IJ47630m2a.230718.epkg.Z

 

Please note that the above table refers to AIX TL/SP level as opposed to fileset level, i.e., 7.3.0.3 is AIX 7300-00-03.

 

Please reference the Affected Products and Version section above for help with checking installed fileset levels.

 

VIOS LevelInterim Fix
3.1.2.40IJ47631m6a.230718.epkg.Z
3.1.2.50IJ47631m6a.230718.epkg.Z
3.1.2.60IJ47631m6a.230718.epkg.Z
3.1.3.21IJ47632m4a.230718.epkg.Z
3.1.3.30IJ47632m4a.230718.epkg.Z
3.1.3.40IJ47632m4a.230718.epkg.Z
3.1.4.10IJ47597m6a.230717.epkg.Z
3.1.4.21IJ47597m6a.230717.epkg.Z

 

To extract the fixes from the tar file:

tar xvf libxml2_fix5.tar

cd libxml2_fix5

 

Verify you have retrieved the fixes intact:

The checksums below were generated using the "openssl dgst -sha256 [filename]" command as the following:

 

openssl dgst -sha256filename
3d2d1242eb42fadb11d1c3e9625a81bdf3f605a465039b7592d46ab401e68af7IJ47597m4a.230718.epkg.Z
c06c96eeae459c2533b0d2df958f31aafbcc6c274a732324039328ee7a272f97IJ47597m6a.230717.epkg.Z
b80ac199295a15227b8e946ff5db42324e62e40bbfbb59d81f5b2627286e505bIJ47629m4a.230718.epkg.Z
85b4de5a3bd7098cb808f48a9ceb40f3aefddae418e902f42691f68882d850c8IJ47630m2a.230718.epkg.Z
a72eb5c8c9012a0a3d9b4789b257e29740720f4a1948c2971d6dafd77ecccadcIJ47631m6a.230718.epkg.Z
38539a5de0ac8961a32bb5e872a79d4bee66b5de6735c9f049f2decc6dac581cIJ47632m4a.230718.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 Support at http://ibm.com/support/ and describe the discrepancy.         

 

openssl dgst -sha256 -verify [pubkey_file] -signature [advisory_file].sig [advisory_file]

openssl dgst -sha256 -verify [pubkey_file] -signature [ifix_file].sig [ifix_file]

 

Published advisory OpenSSL signature file location:

https://aix.software.ibm.com/aix/efixes/security/libxml2_advisory5.asc.sig

 

C. FIX AND INTERIM FIX INSTALLATION

 

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

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References

Complete CVSS v3 Guide
On-line Calculator v3

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Related Information

IBM Secure Engineering Web Portal
IBM Product Security Incident Response Blog

AIX Security Bulletin (ASCII format)

 

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

 

Contact IBM Support for questions related to this announcement:

https://ibm.com/support/

 

For information on how to securely verify AIX security bulletins and fixes:

https://www.ibm.com/support/pages/node/6985269

 

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_…

https://aix.software.ibm.com/aix/efixes/security/systems_p_os_aix_security_pubkey.txt

 

To verify the AIX/VIOS security bulletin:

Published advisory OpenSSL signature file location:

https://aix.software.ibm.com/aix/efixes/security/libxml2_advisory5.asc.sig

 

openssl dgst -sha256 -verify [pubkey_file] -signature [advisory_file].sig [advisory_file]

 

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

Acknowledgement

Change History

25 Jul 2023: Initial Publication

*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. In addition to other efforts to address potential vulnerabilities, IBM periodically updates the record of components contained in our product offerings. As part of that effort, if IBM identifies previously unidentified packages in a product/service inventory, we address relevant vulnerabilities regardless of CVE date. Inclusion of an older CVEID does not demonstrate that the referenced product has been used by IBM since that date, nor that IBM was aware of a vulnerability as of that date. We are making clients aware of relevant vulnerabilities as we become aware of them. "Affected Products and Versions" referenced in IBM Security Bulletins are intended to be only products and versions that are supported by IBM and have not passed their end-of-support or warranty date. Thus, failure to reference unsupported or extended-support products and versions in this Security Bulletin does not constitute a determination by IBM that they are unaffected by the vulnerability. Reference to one or more unsupported versions in this Security Bulletin shall not create an obligation for IBM to provide fixes for any unsupported or extended-support products or versions.

Document Location

Worldwide

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Document Information

Modified date:
11 October 2023

UID

ibm17014485

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