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[IBM] Schwachstelle im IBM AIX ftp Kommando
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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 IBM AIX ftp Kommando
Im SetUID ftp Kommando in IBM AIX Version 5.2 und 5.3 kann ein Buffer
Overflow ausgeloest werden. Ein lokaler Angreifer kann diese
Schwachstelle ausnutzen, um beliebige Befehle mit root-Rechten
ausfuehren. Ein Exploit zum Ausnutzen dieser Schwachstelle ist bereits
veroeffentlicht worden.
Betroffen sind die folgenden Software Pakete und Plattformen:
Fileset bos.net.tcp.client Version 5.2.0.85 - 5.2.0.107 ohne APAR IZ01812
Fileset bos.net.tcp.client Version 5.3.0.40 - 5.3.0.62 ohne APAR IZ01813
Die Verfuegbarkeit von APAR IZ01812 ist angekuendigt fuer den 31.10.2007
Die Verfuegbarkeit von APAR IZ01813 ist angekuendigt fuer den 27.11.2007
Fuer die folgenden AIX Versionen stellt IBM Interim Fixes bereit:
AIX Release & Technology Level Interim fix
---------------------------------------------------------------
5200-08 IZ01812_08.070723.epkg.Z
5200-09 IZ01812_09.070723.epkg.Z
5200-10 IZ01812_10.070723.epkg.Z
5300-04 IZ01813_04.070723.epkg.Z
5300-05 IZ01813_05.070723.epkg.Z
5300-06 IZ01813_06.070723.epkg.Z
IBM AIX 5.2, 5.3
Vom Hersteller werden ueberarbeitete Pakete zur Verfuegung gestellt.
Hersteller Advisory:
http://www14.software.ibm.com/webapp/set2/subscriptions/ijhifoeblist?mode=1
(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,
Klaus Moeller, DFN-CERT
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IBM SECURITY ADVISORY
First Issued: Tue Jul 24 10:03:54 CDT 2007
===============================================================================
VULNERABILITY SUMMARY
VULNERABILITY: AIX ftp gets() Buffer Overflow Vulnerabilities
PLATFORMS: AIX 5.2, 5.3
SOLUTION: Apply the APAR, interim fix or workaround as described
below.
THREAT: An attacker may run arbitrary code as root privileges.
CERT VU Number: n/a
CVE Number: n/a
===============================================================================
DETAILED INFORMATION
I. OVERVIEW
The ftp command uses the File Transfer Protocol (FTP) to transfer files
between the local host and a remote host or between two remote hosts. The
program is installed by default and is setuid.
II. DESCRIPTION
A local vulnerability exists in the client part of the ftp application
whereby a user may execute arbitrary code with root privileges. This is
due to calls to the deprecated routine 'gets()'.
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 | grep bos.net.tcp.client
The following filesets are vulnerable:
AIX Level Lower Level Upper Level
-------------------------------------------------
5.2.0 5.2.0.85 5.2.0.107
5.3.0 5.3.0.40 5.3.0.62
V. SOLUTIONS
A. APARS
IBM provides the following fixes:
AIX Level APAR number Availability
--------------------------------------------------------------------
5.2.0 IZ01812 10/31/2007 (subject to change)
5.3.0 IZ01813 11/27/2007 (subject to change)
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/ftpgets_ifix.tar.Z
This is a compressed tarball containing this 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 Release & Technology Level Interim fix
---------------------------------------------------------------
5200-08 IZ01812_08.070723.epkg.Z
5200-09 IZ01812_09.070723.epkg.Z
5200-10 IZ01812_10.070723.epkg.Z
5300-04 IZ01813_04.070723.epkg.Z
5300-05 IZ01813_05.070723.epkg.Z
5300-06 IZ01813_06.070723.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.
Customers install the interim fix and operate the modified version of
AIX at their own risk.
Verify you have retrieved the fixes intact:
The interim fixes below are named by using the technology level
corresponding to the release that the fix applies to. The checksums
below were generated using the "sum" and "md5sum" commands and are as
follows:
Filename sum md5sum
----------------------------------------------------------------------
IZ01812_08.070723.epkg.Z 64692 123 a2f21e469e0b64a99455bd3ef0b86484
IZ01812_09.070723.epkg.Z 18190 123 6a1e448cf3211bc5a323064d45bfb8eb
IZ01812_10.070723.epkg.Z 45986 126 babccdd3a10113a3611995af8e49062c
IZ01813_04.070723.epkg.Z 00288 126 bc0e7084191fd4672475bf4da9dfc494
IZ01813_05.070723.epkg.Z 58925 126 dc83cce43dcb7654ab9d4f82b7b588f8
IZ01813_06.070723.epkg.Z 36147 129 e0ee8317805a5120a64e72ae49522657
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
Due to the nature of ftp there are not many workarounds. If the program is
not necessary, the following options are available.
A. OPTION 1
Install openssl and openssh and take advantage of the secure copy 'scp'
command to transfer files between systems.
B. OPTION 2
Remove the setuid bit with the following command:
# chmod 555 /usr/bin/ftp
NOTE: This will effectively remove functionality from 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
VII. 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 send email to
security-alert@xxxxxxxxxxxxxx with a subject of "get key". The key
can also be downloaded from a PGP Public Key Server. The key id is
0x4265D862.
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.
VIII. ACKNOWLEDGMENTS
iDefense (http://labs.idefense.com/) credits an anonymous contributer.
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- --
Dipl. Inform. Klaus Moeller (CSIRT)
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
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