Summary

There is a vulnerability in tcpdump that affects AIX.

Vulnerability Details

CVEID: CVE-2018-19519 DESCRIPTION: Tcpdump is vulnerable to a stack-based buffer overflow, caused by improper bounds checking by the print_prefix function of print-hncp.c. By using a specially-crafted packet data, a remote attacker could overflow a buffer and execute arbitrary code on the system or cause the application to crash.
CVSS Base Score: 7.3
CVSS Temporal Score: See <https://exchange.xforce.ibmcloud.com/vulnerabilities/153314&gt; for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L)

Affected Products and Versions

AIX 7.1, 7.2

VIOS 2.2.x

The following fileset levels are vulnerable:

key_fileset = aix

Fileset Lower Level Upper Level KEY
---------------------------------------------------------
bos.net.tcp.server 6.1.9.300 6.1.9.400 key_w_fs
bos.net.tcp.server 7.1.4.32 7.1.4.34 key_w_fs
bos.net.tcp.server 7.1.5.0 7.1.5.31 key_w_fs
bos.net.tcp.tcpdump 7.2.1.1 7.2.1.3 key_w_fs
bos.net.tcp.tcpdump 7.2.2.0 7.2.2.16 key_w_fs
bos.net.tcp.tcpdump 7.2.3.0 7.2.3.15 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.server

Remediation/Fixes

A. APARS

IBM has assigned the following APARs to this problem:

AIX Level APAR Availability SP KEY
-----------------------------------------------------
7.1.4 IJ12979 ** SP08-1914 key_w_apar
7.1.5 IJ12980 ** SP04-1913 key_w_apar
7.2.1 IJ12981 ** SP06-1914 key_w_apar
7.2.2 IJ12982 ** SP04-1914 key_w_apar
7.2.3 IJ12983 ** SP03-1913 key_w_apar

VIOS Level APAR Availability SP KEY
----------------------------------------------------
2.2.5 IJ12978 ** 2.2.5.60 key_w_apar
2.2.6 IJ12978 ** 2.2.6.40 key_w_apar
3.1.0 IJ12983 ** 3.1.0.20 key_w_apar

Subscribe to the APARs here:

http://www.ibm.com/support/docview.wss?uid=isg1IJ12978
https://www.ibm.com/support/docview.wss?uid=isg1IJ12979
https://www.ibm.com/support/docview.wss?uid=isg1IJ12980
https://www.ibm.com/support/docview.wss?uid=isg1IJ12981
https://www.ibm.com/support/docview.wss?uid=isg1IJ12982
https://www.ibm.com/support/docview.wss?uid=isg1IJ12983

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 fixes are available.

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

ftp://aix.software.ibm.com/aix/efixes/security/tcpdump_fix4.tar
http://aix.software.ibm.com/aix/efixes/security/tcpdump_fix4.tar
https://aix.software.ibm.com/aix/efixes/security/tcpdump_fix4.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
----------------------------------------------
7.1.4.5 IJ12979m5a.190304.epkg.Z key_w_fix
7.1.4.6 IJ12979m6a.190304.epkg.Z key_w_fix
7.1.4.7 IJ12979m7a.190205.epkg.Z key_w_fix
7.1.5.1 IJ12980m1a.190207.epkg.Z key_w_fix
7.1.5.2 IJ12980m2a.190212.epkg.Z key_w_fix
7.1.5.3 IJ12980m3a.190212.epkg.Z key_w_fix
7.2.1.3 IJ12981m3a.190214.epkg.Z key_w_fix
7.2.1.4 IJ12981m4a.190215.epkg.Z key_w_fix
7.2.1.5 IJ12981m5a.190225.epkg.Z key_w_fix
7.2.2.1 IJ12982m1a.190215.epkg.Z key_w_fix
7.2.2.2 IJ12982m2a.190215.epkg.Z key_w_fix
7.2.2.3 IJ12982m3a.190215.epkg.Z key_w_fix
7.2.3.0 IJ12983m0a.190215.epkg.Z key_w_fix
7.2.3.1 IJ12983m1a.190215.epkg.Z key_w_fix
7.2.3.2 IJ12983m2a.190215.epkg.Z key_w_fix

Please note that the above table refers to AIX TL/SP level as opposed to fileset level, i.e., 7.2.2.3 is AIX 7200-02-03. Please reference the Affected Products and Version section above for help with checking installed fileset levels.

VIOS Level Interim Fix (*.Z) KEY
-----------------------------------------------
2.2.5.40 IJ12978s9a.190215.epkg.Z key_w_fix
2.2.5.50 IJ12978s9a.190215.epkg.Z key_w_fix
2.2.6.21 IJ12978sBa.190215.epkg.Z key_w_fix
2.2.6.23 IJ12978sBa.190215.epkg.Z key_w_fix

2.2.6.31 IJ12978sCa.190215.epkg.Z key_w_fix
2.2.6.32 IJ12978sCa.190215.epkg.Z key_w_fix
3.1.0.10 IJ12983m2a.190215.epkg.Z key_w_fix

To extract the fixes from the tar file:

tar xvf tcpdump_fix4.tar
cd tcpdump_fix4

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
-----------------------------------------------------------------------------------------------------
2e05ddb65cb649d7c68342573823c7aca9febbf55ac4e4b761c6cc3429f9c472 IJ12978s9a.190215.epkg.Z key_w_csum
819ab2731f480d654db43159adf92176726edbc9377769e0215461713c933714 IJ12978sBa.190215.epkg.Z key_w_csum
216fc77d43f0713873ccb0cc7b5f531216245e4eefc02ca07b56b763ddf0c5da IJ12978sCa.190215.epkg.Z key_w_csum
8a8c3ba84781f2b0f007ac93568a629be5bd65119b7b76a75f4c80496f8193ed IJ12979m5a.190304.epkg.Z key_w_csum
a8f82929828046dabbfe0f22b998026878254b31948e943ba7487d8b12ab598b IJ12979m6a.190304.epkg.Z key_w_csum
959cc124a81763c57bd1c9576f8c180a581f7685a9b6ee17e517f9863dc5f7c7 IJ12979m7a.190205.epkg.Z key_w_csum
50eb9a6281393c0f4464c54e984fc66cb3be0ed931b2e828b6ca9a38c5477b03 IJ12980m1a.190207.epkg.Z key_w_csum
5d8fba67e88068dba76fbd7dd6ee4fc8d01de2e4c1b5fd99ce672624ab62b2bc IJ12980m2a.190212.epkg.Z key_w_csum
0c0790166da0f92f198abfe50255a9282c458a8f3f8158b17660512e67de8003 IJ12980m3a.190212.epkg.Z key_w_csum
1d25c5255cf39f872e516e2e312894bf9677e6d1062a74ba5b792425647032c7 IJ12981m3a.190214.epkg.Z key_w_csum
a2932c10a0755981827ef6f105e5d393c29a91766de28e99a442f3845f505227 IJ12981m4a.190215.epkg.Z key_w_csum
cae215ce40cf9bd51f4fbbdee172258a1b24143cf1004e30b102416b359a4a87 IJ12981m5a.190225.epkg.Z key_w_csum
2f94de4c9d3fc3aaf55aa923fb8cc25054b436d28b03a8e145f2197d74938e95 IJ12982m1a.190215.epkg.Z key_w_csum
5ea43c493fdeb5889a58a138b7050de20e6ef776a39c2def0fc06c58bc227940 IJ12982m2a.190215.epkg.Z key_w_csum
1a8bbeed0a375739b133c317099ab938a43f670a355fd76f16641a640c7039d3 IJ12982m3a.190215.epkg.Z key_w_csum
b1d3979a1e9a5c1ed90a15d24974ba80430573e0ae61ee967d4c7304bdef8c94 IJ12983m0a.190215.epkg.Z key_w_csum
1e48107063297522366390de5eb1648a1d98edbaf3092bddf8aecec6ce45af6b IJ12983m1a.190215.epkg.Z key_w_csum
b87249e90504d241f9359c66f16527e2cd73c1b50a05199d4968ad5a79f10af7 IJ12983m2a.190215.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/tcpdump_advisory4.asc.sig
https://aix.software.ibm.com/aix/efixes/security/tcpdump_advisory4.asc.sig
ftp://aix.software.ibm.com/aix/efixes/security/tcpdump_advisory4.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.