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Security Bulletin: Vulnerability in BIND affects AIX (CVE-2021-25219)

Security Bulletin


Summary

UPDATED Mar 16 (See Change History - New iFixes Provided): There is a vulnerability in BIND that affects AIX.

Vulnerability Details

CVEID:   CVE-2021-25219
DESCRIPTION:   ISC BIND is vulnerable to a denial of service, caused by a flaw in response processing. By abusing a lame cache, an attacker could exploit this vulnerability to cause a named resolver to spend most of its CPU time on managing and checking the lame cache and severely degrade resolver performance.
CVSS Base score: 5.3
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/212375 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)

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.bind7.2.5.1007.2.5.100
bos.net.tcp.bind_utils7.2.5.1007.2.5.100
bos.net.tcp.bind7.3.0.07.3.0.0
bos.net.tcp.bind_utils7.3.0.07.3.0.0

 

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
7.1.5IJ37222SP10
7.2.4IJ37225SP06
7.2.5IJ37223SP04
7.3.0IJ37226SP02

 

VIOS LevelAPARSP
3.1.1IJ372253.1.1.60
3.1.2IJ372243.1.2.40
3.1.3IJ372233.1.3.20

 

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
 
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
7.1.5.7IJ37222m9c.220315.epkg.Z
7.1.5.8IJ37222m9c.220315.epkg.Z
7.1.5.9IJ37222m9c.220315.epkg.Z
7.2.4.3IJ37225m5c.220315.epkg.Z
7.2.4.4IJ37225m5c.220315.epkg.Z
7.2.4.5IJ37225m5c.220315.epkg.Z
7.2.5.1IJ37224m3c.220315.epkg.Z
7.2.5.2IJ37224m3c.220315.epkg.Z
7.2.5.3IJ37224m3c.220315.epkg.Z
7.3.0.1IJ37226s1b.220315.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
3.1.1.30IJ37225m5c.220315.epkg.Z
3.1.1.40IJ37225m5c.220315.epkg.Z
3.1.1.50IJ37225m5c.220315.epkg.Z
3.1.2.10IJ37224m3c.220315.epkg.Z
3.1.2.21IJ37224m3c.220315.epkg.Z
3.1.3.10IJ37224m3c.220315.epkg.Z
3.1.3.14IJ37224m3c.220315.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_fix20.tar
cd bind_fix20
 
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
c97ca6a6f08834de85adf24854956cb23cc948b5fab83b87ed9314b49fedb97dIJ37222m9c.220315.epkg.Z
1b664c2db58503d69141d34e5b11165ce110d7b5150b228c9cd4ba6172094042IJ37224m3c.220315.epkg.Z
d0af2eab502a4ed848326db6d4af6680ad4fa015225cea58aacc807b8ff3b0f8IJ37225m5c.220315.epkg.Z
6dab0239b497eab26d75a2b8cf5715b9d4c74cb10a1ae835b229dbf5037c12c0IJ37226s1b.220315.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

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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)

Acknowledgement

Change History

1 Mar 2022: Initial Publication
Updated: Wed Mar 16 11:31:17 CDT 2022
Update: New iFixes provided for all AIX and VIOS levels.
The previous iFixes were not cumulative, and the new iFixes are intended to supplant the previous fixes.

*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

Review the IBM security bulletin disclaimer and definitions regarding your responsibilities for assessing potential impact of security vulnerabilities to your environment.

Document Location

Worldwide

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Document Information

Modified date:
16 March 2022

UID

ibm16560382

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