Security Bulletin
Summary
There are vulnerabilities in BIND that affect AIX.
Vulnerability Details
CVEID: CVE-2020-8617
DESCRIPTION: ISC BIND is vulnerable to a denial of service, caused by a logic error in code which checks TSIG validity. A remote attacker could exploit this vulnerability to trigger an assertion failure in tsig.c.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/182127 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-2020-8616
DESCRIPTION: ISC BIND is vulnerable to a denial of service, caused by the failure to limit the number of fetches performed when processing referrals. By using specially crafted referrals, a remote attacker could exploit this vulnerability to cause the recursing server to issue a very large number of fetches in an attempt to process the referral.
CVSS Base score: 8.6
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/182126 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H)
Affected Products and Versions
| Affected Product(s) | Version(s) |
| AIX | 7.1 |
| AIX | 7.2 |
| VIOS | 2.2 |
| VIOS | 3.1 |
The following fileset levels are vulnerable:
key_fileset = aix
Fileset Lower Level Upper Level KEY
---------------------------------------------------------
bos.net.tcp.client 6.1.9.0 6.1.9.404 key_w_fs
bos.net.tcp.client 7.1.5.0 7.1.5.35 key_w_fs
bos.net.tcp.bind_utils 7.2.2.0 7.2.2.18 key_w_fs
bos.net.tcp.bind_utils 7.2.3.0 7.2.3.16 key_w_fs
bos.net.tcp.bind_utils 7.2.4.0 7.2.4.1 key_w_fs
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.client
Remediation/Fixes
A. APARS
IBM has assigned the following APARs to this problem:
AIX Level APAR Availability SP KEY
-----------------------------------------------------
7.1.5 IJ25924 ** SP07-2037 key_w_apar
7.2.2 IJ25925 ** N/A key_w_apar
7.2.3 IJ25926 ** SP06-2038 key_w_apar
7.2.4 IJ25927 ** SP03-2038 key_w_apar
VIOS Level APAR Availability SP KEY
----------------------------------------------------
2.2.6 IJ26021 ** N/A key_w_apar
3.1.0 IJ25926 ** 3.1.0.50 key_w_apar
3.1.1 IJ25927 ** 3.1.1.30 key_w_apar
Subscribe to the APARs here:
http://www.ibm.com/support/pages/apar/IJ25924
http://www.ibm.com/support/pages/apar/IJ25925
http://www.ibm.com/support/pages/apar/IJ25926
http://www.ibm.com/support/pages/apar/IJ25927
http://www.ibm.com/support/pages/apar/IJ26021
https://www.ibm.com/support/pages/apar/IJ25924
https://www.ibm.com/support/pages/apar/IJ25925
https://www.ibm.com/support/pages/apar/IJ25926
https://www.ibm.com/support/pages/apar/IJ25927
https://www.ibm.com/support/pages/apar/IJ26021
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:
ftp://aix.software.ibm.com/aix/efixes/security/bind_fix17.tar
http://aix.software.ibm.com/aix/efixes/security/bind_fix17.tar
https://aix.software.ibm.com/aix/efixes/security/bind_fix17.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 Level Interim Fix (*.Z) KEY
----------------------------------------------
7.1.5.4 IJ25924s6a.200708.epkg.Z key_w_fix
7.1.5.5 IJ25924s6a.200708.epkg.Z key_w_fix
7.1.5.6 IJ25924s6a.200708.epkg.Z key_w_fix
7.2.2.4 IJ25925s6a.200708.epkg.Z key_w_fix
7.2.2.5 IJ25925s6a.200708.epkg.Z key_w_fix
7.2.2.6 IJ25925s6a.200708.epkg.Z key_w_fix
7.2.3.3 IJ25926s5a.200708.epkg.Z key_w_fix
7.2.3.4 IJ25926s5a.200708.epkg.Z key_w_fix
7.2.3.5 IJ25926s5a.200708.epkg.Z key_w_fix
7.2.4.0 IJ25927s2a.200708.epkg.Z key_w_fix
7.2.4.1 IJ25927s2a.200708.epkg.Z key_w_fix
7.2.4.2 IJ25927s2a.200708.epkg.Z key_w_fix
Please note that the above table refers to AIX TL/SP level as opposed to fileset level, i.e., 7.2.3.5 is AIX 7200-03-05.
Please reference the Affected Products and Version section above for help with checking installed fileset levels.
VIOS Level Interim Fix (*.Z) KEY
-----------------------------------------------
2.2.6.40 IJ26021sDa.200708.epkg.Z key_w_fix
2.2.6.41 IJ26021sDa.200708.epkg.Z key_w_fix
2.2.6.50 IJ26021sDa.200708.epkg.Z key_w_fix
2.2.6.51 IJ26021sDa.200708.epkg.Z key_w_fix
2.2.6.60 IJ26021sDa.200708.epkg.Z key_w_fix
2.2.6.61 IJ26021sDa.200708.epkg.Z key_w_fix
2.2.6.65 IJ26021sDa.200708.epkg.Z key_w_fix
3.1.0.20 IJ25926s5a.200708.epkg.Z key_w_fix
3.1.0.30 IJ25926s5a.200708.epkg.Z key_w_fix
3.1.0.40 IJ25926s5a.200708.epkg.Z key_w_fix
3.1.1.0 IJ25927s2a.200708.epkg.Z key_w_fix
3.1.1.10 IJ25927s2a.200708.epkg.Z key_w_fix
3.1.1.20 IJ25927s2a.200708.epkg.Z key_w_fix
3.1.1.21 IJ25927s2a.200708.epkg.Z key_w_fix
3.1.1.22 IJ25927s2a.200708.epkg.Z key_w_fix
3.1.1.25 IJ25927s2a.200708.epkg.Z key_w_fix
To extract the fixes from the tar file:
tar xvf bind_fix17.tar
cd bind_fix17
Verify you have retrieved the fixes intact:
The checksums below were generated using the "openssl dgst -sha256 [filename]" command as the following:
openssl dgst -sha256 filename KEY
-----------------------------------------------------------------------------------------------------
1b952357d1691d203c13d888760553743269a7b84e3432131bab9a6a919a53a7 IJ25924s6a.200708.epkg.Z key_w_csum
5f221cb2ee211f02256d5e88c8a5962aed7a97ae6683a6eaf3724fe81eef0fe8 IJ25925s6a.200708.epkg.Z key_w_csum
e9b46105c1713fc1944b55fd3d637d912feaec439865bcc23a91c8f739ea5535 IJ25926s5a.200708.epkg.Z key_w_csum
d8a02e72780156eca420977627bb7c80455afc6e4b3d40a0e5cb5c6a72c4cfaa IJ25927s2a.200708.epkg.Z key_w_csum
974e499efc70808300e1e7bb7af7706765a6ccd040c5e76944a52b727c0f5dd7 IJ26021sDa.200708.epkg.Z key_w_csum
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 -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/bind_advisory17.asc.sig
https://aix.software.ibm.com/aix/efixes/security/bind_advisory17.asc.sig
ftp://aix.software.ibm.com/aix/efixes/security/bind_advisory17.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
Get Notified about Future Security Bulletins
References
Change History
21 Aug 2020: 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
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:
21 August 2020
UID
ibm16320325