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Security Bulletin: AIX is vulnerable to cache poisoning due to ISC BIND (CVE-2021-25220)

Security Bulletin


Summary

A vulnerability in ISC BIND could allow a remote attacker to poison the cache (CVE-2021-25220). AIX uses ISC BIND as part of its DNS functions.

Vulnerability Details

CVEID:   CVE-2021-25220
DESCRIPTION:   ISC BIND could allow a remote attacker to bypass security restrictions, caused by an error when using DNS forwarders. An attacker could exploit this vulnerability to poison the cache with incorrect records leading to queries being made to the wrong servers, which might also result in false information being returned to clients.
CVSS Base score: 6.8
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/221991 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/A:N)

Affected Products and Versions

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

 

The following fileset levels are vulnerable:

 

FilesetLower LevelUpper Level
bos.net.tcp.server7.1.5.07.1.5.35
bos.net.tcp.client7.1.5.07.1.5.40
bos.net.tcp.bind7.2.4.07.2.4.1
bos.net.tcp.bind_utils7.2.4.07.2.4.3
bos.net.tcp.bind7.2.5.07.2.5.1
bos.net.tcp.bind_utils7.2.5.07.2.5.2
bos.net.tcp.bind7.2.5.1007.2.5.101
bos.net.tcp.bind_utils7.2.5.1007.2.5.101
bos.net.tcp.bind7.3.0.07.3.0.1
bos.net.tcp.bind_utils7.3.0.07.3.0.1

 

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.net.tcp.server
 

Remediation/Fixes

A. APARS
            
IBM has assigned the following APARs to this problem:
 
AIX LevelAPARSP
7.1.5IJ40617SP11
7.2.4IJ40616N/A
7.2.5IJ40674SP05
7.3.0IJ40614SP03

 

VIOS LevelAPARSP
3.1.1IJ40616N/A
3.1.2IJ406153.1.2.40
3.1.3IJ411393.1.3.30

 

Subscribe to the APARs here:
 
 
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 AIX and VIOS fixes can be downloaded via ftp or http from:
 
 
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
7.1.5.7IJ40617m9b.220718.epkg.Z
7.1.5.8IJ40617m9b.220718.epkg.Z
7.1.5.9IJ40617m9b.220718.epkg.Z
7.2.4.3IJ40616m5b.220718.epkg.Z
7.2.4.4IJ40616m5b.220718.epkg.Z
7.2.4.5IJ40616m5b.220718.epkg.Z
7.2.5.2IJ40615m4b.220718.epkg.Z
7.2.5.3IJ40615m4b.220718.epkg.Z
7.2.5.4IJ40615m4b.220718.epkg.Z
7.3.0.1IJ40614m2b.220718.epkg.Z
7.3.0.2IJ40614m2b.220718.epkg.Z
 
Please note that the above table refers to AIX TL/SP level as opposed to fileset level, i.e., 7.2.5.2 is AIX 7200-05-02.
 
Please reference the Affected Products and Version section above for help with checking installed fileset levels.
 
VIOS LevelInterim Fix
3.1.1.30IJ40616m5b.220718.epkg.Z
3.1.1.40IJ40616m5b.220718.epkg.Z
3.1.1.50IJ40616m5b.220718.epkg.Z
3.1.2.10IJ40615m4b.220718.epkg.Z
3.1.2.21IJ40615m4b.220718.epkg.Z
3.1.3.10IJ40615m4b.220718.epkg.Z
3.1.3.14IJ40615m4b.220718.epkg.Z
3.1.3.21IJ40615m4b.220718.epkg.Z

 

The above fixes are cumulative and address previously issued AIX/VIOS BIND security bulletins.
 
To extract the fixes from the tar file:
 
tar xvf bind_fix21.tar
cd bind_fix21
 
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
6c62ac5b0598ac3117445cfc5797aa6b85c4f527572e32d31d147849803b61ceIJ40614m2b.220718.epkg.Z
93bcac519d552563e6b4fa1f74712c6acf2b0c218d59be98dd1d8ad2cfcf3b21IJ40615m4b.220718.epkg.Z
33b06edaae5964176f6c6d7ea58a97d2dbd142ee0817f56b16bcbb03b9a500d4IJ40616m5b.220718.epkg.Z
199c9caa64e4fac6822e7ea11bde174cfddaaf00deb8ac294d86b9e512aed418IJ40617m9b.220718.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:
 
 
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:
 
 
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

Get Notified about Future Security Bulletins

References

Off

Acknowledgement

Change History

28 Jul 2022: 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:
28 July 2022

UID

ibm16607880