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[IBM] Schwachstelle in tftp - ibm2007103109
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Liebe Kolleginnen und Kollegen,
soeben erreichte uns nachfolgende Warnung des IBM Managed Security
Services. Wir geben diese Informationen unveraendert an Sie weiter.
Buffer Overflow im AIX tftp Kommando
Im AIX tftp Kommando laesst sich ein Buffer Overflow ausloesen. Da das
Kommando SetUID installiert ist, koennen lokale Angreifer die
Schwachstelle dazu ausnutzen, beliebigen Code mit root-Rechten auszu
fuehren.
Betroffen sind die folgenden Software Pakete und Plattformen:
Fileset bos.net.tcp.client auf AIX 5.2.0 Version 5.2.0.0 - 5.2.0.107
ohne APAR IZ03054
Fileset bos.net.tcp.client auf AIX 5.3.0 Version 5.3.0.0 - 5.3.0.63
ohne APAR IZ03060
AIX 5.2, 5.3
Vom Hersteller werden ueberarbeitete Pakete zur Verfuegung gestellt.
Hersteller Advisory:
https://techsupport.services.ibm.com/server/pseries.subscriptionSvcs
(c) der deutschen Zusammenfassung bei DFN-CERT Services GmbH; die
Verbreitung, auch auszugsweise, ist nur unter Hinweis auf den Urheber,
DFN-CERT Services GmbH, und nur zu nicht kommerziellen Zwecken
gestattet.
Mit freundlichen Gruessen,
Andreas Bunten, DFN-CERT
- --
Andreas Bunten (CSIRT), +49 40 808077-555
DFN-CERT Services GmbH, https://www.dfn-cert.de, Phone +49 40 808077-555
Sitz / Register: Hamburg, AG Hamburg, HRB 88805, Ust-IdNr.: DE 232129737
Heidenkampsweg 41, 20097 Hamburg/Germany, CEO: Dr. Klaus-Peter Kossakowski
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IBM SECURITY ADVISORY
First Issued: Mon Oct 29 11:24:49 CDT 2007
===============================================================================
VULNERABILITY SUMMARY
VULNERABILITY: AIX tftp buffer overflow vulnerability
PLATFORMS: AIX 5.2, 5.3
SOLUTION: Apply the APAR, interim fix or workaround as
described below.
THREAT: A local attacker may run arbitrary code with root
privileges.
CERT VU Number: n/a
CVE Number: n/a
===============================================================================
DETAILED INFORMATION
I. OVERVIEW
The tftp and utftp commands transfer files between hosts using the
Trivial File Transfer Protocol (TFTP). The primary fileset for
the AIX tftp system is 'bos.net.tcp.client'. The tftp command
provided by this fileset contains a buffer overflow vulnerability.
II. DESCRIPTION
A buffer overflow vulnerability exists in the 'bos.net.tcp.client'
fileset command listed below. A local attacker may execute
arbitrary code with root privileges because the command is setuid
root.
The following 'bos.net.tcp.client' command is vulnerable:
/usr/bin/tftp
III. IMPACT
The successful exploitation of this vulnerability allows a
non-privileged user to execute code with root privileges.
IV. PLATFORM VULNERABILITY ASSESSMENT
To determine if your system is vulnerable, run the following
command:
# lslpp -l bos.net.tcp.client
The following fileset levels are vulnerable:
AIX Fileset AIX Level Lower Level Upper Level
----------------------------------------------------------------
bos.net.tcp.client 5.2.0 5.2.0.0 5.2.0.107
bos.net.tcp.client 5.3.0 5.3.0.0 5.3.0.63
NOTE: IBM only supports the latest two releases (AIX 5.2 and 5.3)
and the latest three Technology Levels (AIX 5.2 TL08, TL09, TL10
and AIX 5.3 TL04, TL05, TL06). Affected customers are urged to
upgrade to the latest applicable Technology Level and Service
Pack.
V. SOLUTIONS
A. APARS
IBM provides the following fixes:
AIX Level APAR number Availability
--------------------------------------------------------------------
5.2.0 IZ03054 Available now
5.3.0 IZ03060 Available now
Subscribe to the APARs here:
http://www.ibm.com/support/docview.wss?uid=isg1IZ03054
http://www.ibm.com/support/docview.wss?uid=isg1IZ03060
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.
AIX Version 5 APARs can be downloaded from:
http://www.ibm.com/servers/eserver/support/unixservers/aixfixes.html
NOTE: Affected customers are urged to upgrade to the latest
applicable Technology Level and Service Pack.
B. INTERIM FIXES
Interim fixes are available. The interim fix can be
downloaded via ftp from:
ftp://aix.software.ibm.com/aix/efixes/security/tftp_ifix.tar
The link above is to a tar file containing this signed
advisory, interim fix packages, and PGP signatures for each
package. The interim fixes below include prerequisite
checking. This will enforce the correct mapping between the
fixes and AIX Technology Levels.
AIX Fileset AIX Release and Interim fix
Technology Level
-----------------------------------------------------------------
bos.net.tcp.client 5200-08 IZ03054_08.070821.epkg.Z
bos.net.tcp.client 5200-09 IZ03054_09.070821.epkg.Z
bos.net.tcp.client 5200-10 IZ03054_10.070821.epkg.Z
bos.net.tcp.client 5300-04 IZ03060_04.070821.epkg.Z
bos.net.tcp.client 5300-05 IZ03060_05.070821.epkg.Z
bos.net.tcp.client 5300-06 IZ03060_06.070928.epkg.Z
IMPORTANT: If possible, it is recommended that a mksysb backup
of the system be created. Verify it is both bootable and
readable before proceeding.
These interim fixes have not been fully regression tested;
thus, IBM does not warrant the fully correct functionality of
the interim fix.
Verify you have retrieved the fixes intact:
The checksums below were generated using the "sum", "cksum",
"csum -h MD5" (md5sum), and "csum -h SHA1" (sha1sum) commands
and are as follows:
sum filename
------------------------------------
04749 22 IZ03054_08.070821.epkg.Z
56543 22 IZ03054_09.070821.epkg.Z
64149 22 IZ03054_10.070821.epkg.Z
13231 23 IZ03060_04.070821.epkg.Z
46125 23 IZ03060_05.070821.epkg.Z
31723 23 IZ03060_06.070928.epkg.Z
cksum filename
------------------------------------------
3661048274 21888 IZ03054_08.070821.epkg.Z
1204750745 21894 IZ03054_09.070821.epkg.Z
2878043571 21887 IZ03054_10.070821.epkg.Z
3358063349 22912 IZ03060_04.070821.epkg.Z
3940357421 23005 IZ03060_05.070821.epkg.Z
2677858006 22858 IZ03060_06.070928.epkg.Z
csum -h MD5 (md5sum) filename
----------------------------------------------------------
4f554e71cd000d0253be85182ba79e2a IZ03054_08.070821.epkg.Z
14e8b4a6646acab2347d1ad6b3d64353 IZ03054_09.070821.epkg.Z
d8ceba3dec52bcee027d49313d3098e9 IZ03054_10.070821.epkg.Z
48362dbdc9b95bb26fb34b01c20f70ae IZ03060_04.070821.epkg.Z
f8e5ee8f3635078cb2d9616cbf6a8e0a IZ03060_05.070821.epkg.Z
9aa6c945b0ba011c0a07518a93830865 IZ03060_06.070928.epkg.Z
csum -h SHA1 (sha1sum) filename
------------------------------------------------------------------
7268c2b96de06da2b36bb6011a60e1e8e2940003 IZ03054_08.070821.epkg.Z
0c2d9380f21bfe9789ecd62c475da19d7cf18fb6 IZ03054_09.070821.epkg.Z
3785d112a98cfa4e7c67bee9017c3e0f9191a384 IZ03054_10.070821.epkg.Z
2c32044ae5f8234b3a869a376712c52ae0c4b0ac IZ03060_04.070821.epkg.Z
705049070c9539486cdd285c56bee75c48664bef IZ03060_05.070821.epkg.Z
b7688fd39f967f2d8d7d565625ab1d625a24af64 IZ03060_06.070928.epkg.Z
To verify the sums, use the text of this advisory as input to
csum, md5sum, or sha1sum. For example:
csum -h SHA1 -i Advisory.asc
md5sum -c Advisory.asc
sha1sum -c Advisory.asc
These sums should match exactly. The PGP signatures in the
compressed tarball and on this advisory can also be used to
verify the integrity of the various files they correspond to.
If the sums or signatures cannot be confirmed, double check
the command results and the download site address. If those
are OK, contact IBM AIX Security at
security-alert@xxxxxxxxxxxxxx and describe the discrepancy.
C. INTERIM FIX INSTALLATION
These packages use the new Interim Fix Management Solution to
install and manage interim fixes. More information can be
found at:
http://www14.software.ibm.com/webapp/set2/sas/f/aix.efixmgmt/home.html
To preview an epkg interim fix installation execute the
following command:
# emgr -e ipkg_name -p # where ipkg_name is the name of the
# interim fix package being previewed.
To install an epkg interim fix package, execute the following
command:
# emgr -e ipkg_name -X # where ipkg_name is the name of the
# interim fix package being installed.
The "X" flag will expand any filesystems if required.
VI. WORKAROUNDS
Change the permissions of this command to remove the setuid bit
using the following command:
# chmod 500 /usr/bin/tftp
NOTE: This will disable functionality of this command for all
users except root.
VII. OBTAINING FIXES
AIX Version 5 APARs can be downloaded from:
http://www.ibm.com/servers/eserver/support/unixservers/aixfixes.html
Security related Interim Fixes can be downloaded from:
ftp://aix.software.ibm.com/aix/efixes/security
VIII. CONTACT INFORMATION
If you would like to receive AIX Security Advisories via email,
please visit:
http://www14.software.ibm.com/webapp/set2/subscriptions/pqvcmjd
Comments regarding the content of this announcement can be
directed to:
security-alert@xxxxxxxxxxxxxx
To request the PGP public key that can be used to communicate
securely with the AIX Security Team you can either:
A. Send an email with "get key" in the subject line to:
security-alert@xxxxxxxxxxxxxx
B. Download the key from a PGP Public Key Server. The key ID is:
0xA6A36CCC
Please contact your local IBM AIX support center for any
assistance.
eServer is a trademark of International Business Machines
Corporation. IBM, AIX and pSeries are registered trademarks of
International Business Machines Corporation. All other trademarks
are property of their respective holders.
IX. ACKNOWLEDGMENTS
This vulnerability was discovered internal to IBM as part of its
commitment to secure the AIX operating system.
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