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IBM AIX Buffer Overflow in 'reboot' Command Lets Local Users Execute Arbitrary Code
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SecurityTracker Alert ID: 1019602 |
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SecurityTracker URL: http://securitytracker.com/id/1019602
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CVE Reference:
CVE-2008-1601
(Links to External Site)
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Updated: Apr 1 2008
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Original Entry Date: Mar 12 2008
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Impact:
Execution of arbitrary code via local system, Root access via local system
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Fix Available: Yes Vendor Confirmed: Yes
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Version(s): 5.2, 5.3
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Description:
A vulnerability was reported in AIX. A local user can obtain elevated privileges on the target system.
A local user in the 'shutdown' group can can invoke '/usr/sbin/reboot' trigger a stack overflow to execute arbitrary code with root privileges on the target system.
IBM discovered this vulnerability.
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Impact:
A local user in the 'shutdown' gropu can obtain root privileges on the target system.
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Solution:
The vendor has issued a fix:
For 5.2.0: APAR IZ15479
For 5.3.0: APAR IZ15480 (to be available 3/17/2008).
The vendor advisories are available at:
http://www.ibm.com/support/docview.wss?uid=isg1IZ15479
http://www.ibm.com/support/docview.wss?uid=isg1IZ15480
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Vendor URL: www.ibm.com/ (Links to External Site)
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Cause:
Boundary error
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Underlying OS:
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Message History:
None.
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Source Message Contents
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Date: Tue, 11 Mar 2008 20:29:49 -0500
Subject: IBM AIX
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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
IBM SECURITY ADVISORY
First Issued: Tue Mar 11 10:01:36 CDT 2008
===============================================================================
VULNERABILITY SUMMARY
VULNERABILITY: AIX reboot buffer overflow
PLATFORMS: AIX 5.2, 5.3
SOLUTION: Apply the fix or workaround as described below.
THREAT: A local attacker in the shutdown group may execute
arbitrary code.
CVE Number: n/a
Reboot required? NO
Workarounds? YES
Protected by FPM? YES (high, medium, or low)
Protected by SED? YES
===============================================================================
DETAILED INFORMATION
I. DESCRIPTION
The reboot command contains a stack based buffer overflow. A
local attacker in the shutdown group may exploit this overflow to
execute arbitrary code with root privileges because the command is
setuid root.
The following files are vulnerable:
/usr/sbin/reboot
II. PLATFORM VULNERABILITY ASSESSMENT
To determine if your system is vulnerable, execute the following
command:
lslpp -L bos.rte.control
The following fileset levels are vulnerable:
AIX Fileset Lower Level Upper Level
-----------------------------------------------------------
bos.rte.control 5.2.0.85 5.2.0.86
bos.rte.control 5.2.0.95 5.2.0.96
bos.rte.control 5.2.0.105 5.2.0.107
bos.rte.control 5.3.0.50 5.3.0.51
bos.rte.control 5.3.0.60 5.3.0.65
III. SOLUTIONS
A. APARS
IBM has assigned the following APARs to this problem:
AIX Level APAR number Availability
---------------------------------------------------
5.2.0 IZ15479 Now
5.3.0 IZ15480 3/17/2008
Subscribe to the APARs here:
http://www.ibm.com/support/docview.wss?uid=isg1IZ15479
http://www.ibm.com/support/docview.wss?uid=isg1IZ15480
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
Fixes are available. The fixes can be downloaded via ftp
from:
ftp://aix.software.ibm.com/aix/efixes/security/reboot_fix.tar
The link above is to a tar file containing this signed
advisory, fix packages, and PGP 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 Fix (*.U) and Interim Fix (*.Z)
-------------------------------------------------------------------
5.2.0 TL8 IZ15479_08.080304.epkg.Z
5.2.0 TL9 IZ15479_09.080304.epkg.Z
5.2.0 TL10 bos.rte.control.5.2.0.108.U
5.3.0 TL5 IZ15480_05.080304.epkg.Z
5.3.0 TL6 IZ15480_06.080304.epkg.Z
To extract the fixes from the tar file:
tar xvf reboot_fix.tar
cd reboot_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
---------------------------------------
26129 1230 bos.rte.control.5.2.0.108.U
17518 9 IZ15479_08.080304.epkg.Z
06763 9 IZ15479_09.080304.epkg.Z
07673 9 IZ15480_05.080304.epkg.Z
45139 9 IZ15480_06.080304.epkg.Z
cksum filename
---------------------------------------------
808140130 1259520 bos.rte.control.5.2.0.108.U
2710419270 8725 IZ15479_08.080304.epkg.Z
1948359668 8712 IZ15479_09.080304.epkg.Z
1891405268 8631 IZ15480_05.080304.epkg.Z
2577625393 8800 IZ15480_06.080304.epkg.Z
csum -h MD5 (md5sum) filename
-------------------------------------------------------------
b348db57f81460c46e1aba3412d571fb bos.rte.control.5.2.0.108.U
903fa4c1129660394d1e453682a2a9dc IZ15479_08.080304.epkg.Z
9905edf82c0061cfb51d20c5fb4dfee6 IZ15479_09.080304.epkg.Z
0910faf81462969185015a2da8823ffc IZ15480_05.080304.epkg.Z
56e059b6448468a36c07c4e69ca7931c IZ15480_06.080304.epkg.Z
csum -h SHA1 (sha1sum) filename
---------------------------------------------------------------------
92552078a7f489820a6df3ff1431d8a2394e41e8 bos.rte.control.5.2.0.108.U
7bfd16ef7b581acc9c6e2c5b0eb8b1517bc7a8fe IZ15479_08.080304.epkg.Z
b3284aae31fa850e057118af7ba508f046e89964 IZ15479_09.080304.epkg.Z
01ae1a25fbd69a40ff07247ab24647c0fbb8ea3a IZ15480_05.080304.epkg.Z
1dc7ec97ff0df146775da4785860d6b1cd744fc9 IZ15480_06.080304.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 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 AIX Security at
security-alert@austin.ibm.com and describe the discrepancy.
C. FIX AND INTERIM FIX INSTALLATION
IMPORTANT: 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; thus, IBM does not warrant the fully
correct functionality of an interim fix.
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.
IV. WORKAROUNDS
There are two workarounds available.
A. OPTION 1
Change the permissions of these commands to remove the setuid
bit using the following commands:
chmod 500 /usr/sbin/reboot
NOTE: chmod will disable functionality of these commands for
all users except root.
B. OPTION 2 (AIX 6.1, AIX 5.3 TL6 and TL7)
Use the File Permissions Manager (fpm) command to manage
setuid and setgid programs.
fpm documentation can be found in the AIX 6 Security Redbook
at:
http://www.redbooks.ibm.com/abstracts/sg247430.html
An fpm level of high, medium, or low will remove the setuid
bit from the affected commands. For example:
fpm -l high -p # to preview changes
fpm -l high # to execute changes
NOTE: Please review the documentation before execution. fpm
will disable functionality of multiple commands for all users
except root.
V. OBTAINING FIXES
AIX security fixes can be downloaded from:
ftp://aix.software.ibm.com/aix/efixes/security
AIX fixes can be downloaded from:
http://www.ibm.com/eserver/support/fixes/fixcentral/main/pseries/aix
NOTE: Affected customers are urged to upgrade to the latest
applicable Technology Level and Service Pack.
VI. 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@austin.ibm.com
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@austin.ibm.com
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.
VII. ACKNOWLEDGMENTS
IBM discovered and fixed this vulnerability as part of its
commitment to secure the AIX operating system.
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Version: GnuPG v1.4.7 (AIX)
iD8DBQFH1sF+8lficKajbMwRAiVTAKCav3Gu3j5jBy2GskqBg3+YrYYM6ACgsGPH
gQ5OQU2JFkkt71xB1WnuInI=
=+Qn4
-----END PGP SIGNATURE-----
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