-----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. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (AIX) iD8DBQFH1sF+8lficKajbMwRAiVTAKCav3Gu3j5jBy2GskqBg3+YrYYM6ACgsGPH gQ5OQU2JFkkt71xB1WnuInI= =+Qn4 -----END PGP SIGNATURE-----