===================================================================== CERT-Renater Note d'Information No. 2004/VULN190 _____________________________________________________________________ DATE : 29/04/2004 HARDWARE PLATFORM(S) : IBM. OPERATING SYSTEM(S) : AIX 5.1 and 5.2. ====================================================================== IBM SECURITY ADVISORY First Issued: Thu Apr 22 15:17:51 CDT 2004 =========================================================================== VULNERABILITY SUMMARY VULNERABILITY: symlink vulnerabilities in console commands. PLATFORMS: AIX 5.1 and 5.2. SOLUTION: Apply the efixes or APARs as described below. THREAT: A local attacker may cause data destruction or a denial of service. CERT VU Number: N/A CVE Number: N/A =========================================================================== DETAILED INFORMATION I. Description =============== A symlink vulnerability was discovered in some console commands that allow an attacker to overwrite arbitrary system files. This could lead to data destruction or a denial of service. Successful exploitation of this issue would require the root user to execute the vulnerable commands and unintentionally write to the source file of a symbolic link created by the attacker. In some cases a non-root user in the system group may exploit this vulnerability. These issues were discovered internally; at this time there are no known exploits in the wild. The commands affected by these issues ship as part of the bos.rte.console and bos.rte.serv_aid filesets. To determine if these filesets are installed, execute the following commands: # lslpp -L bos.rte.console bos.rte.serv_aid If the filesets are installed they will be listed along with their version information, state, type and a description. II. Impact ========== A local attacker may cause data destruction or a denial of service. III. Solutions =============== A. Official Fix IBM provides the following fixes: APAR number for AIX 5.1.0: IY55790 (available approx. 06/02/04) APAR number for AIX 5.2.0: IY55789 (available approx. 05/19/04) NOTE: Affected customers are urged to upgrade to 5.1.0 or 5.2.0 at the latest maintenance level. B. Emergency Fix Efixes are available for AIX 5.1.0 and 5.2.0. The efixes can be downloaded via ftp from: ftp://aix.software.ibm.com/aix/efixes/security/conscmd_efix.tar.Z conscmd_efix.tar.Z is a compressed tarball containing this advisory, two efix packages for 5.1.0 and 5.2.0 and cleartext PGP signatures for each efix package. Verify you have retrieved the efixes intact: - - -------------------------------------------- The checksums below were generated using the "sum" and "md5sum" commands and are as follows: Filename sum md5 ====================================================================== IY55790.040422.epkg.Z 18401 43 840d68dcd0b7e256896d5f9f05a84e49 IY55789.040422.epkg.Z 22961 40 417bdda79f8e9291efc1cf82522eb552 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@austin.ibm.com and describe the discrepancy. IMPORTANT: If possible, it is recommended that a mksysb backup of the system is created. Verify it is both bootable, and readable before proceeding. These efixes have not been fully regression tested; thus, IBM does not warrant the fully correct functioning of the efix. Customers install the efix and operate the modified version of AIX at their own risk. Efix Installation Instructions: - - ------------------------------- The efix package for AIX 5.1.0 and 5.2.0 are named IY55790.040422.epkg.Z and IY55789.040422.epkg.Z respectively. These packages use the new Emergency Fix Management Solution to install and manage efixes. More information can be found at: http://techsupport.services.ibm.com/server/aix.efixmgmt To preview an epkg efix installation execute the following command: # emgr -e epkg_name -p # where epkg_name is the name of the # efix package being previewed. To install an epkg efix package, execute the following command: # emgr -e epkg_name -X # where epkg_name is the name of the # efix package being installed. The "X" flag will expand any filesystems if required. IV. Obtaining Fixes =================== AIX Version 5 APARs can be downloaded from the eServer pSeries Fix Central web site: http://www-912.ibm.com/eserver/support/fixes/fcgui.jsp Security related Emergency Fixes can be downloaded from: ftp://aix.software.ibm.com/aix/efixes/security V. Contact Information ======================== If you would like to receive AIX Security Advisories via email, please visit: https://techsupport.services.ibm.com/server/pseries.subscriptionSvcs 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 send email to security-alert@austin.ibm.com with a subject of "get key". The key can also be downloaded from a PGP Public Key Server. The key id is 0x3AE561C3. 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. ====================================================================== ========================================================= Les serveurs de référence du CERT-Renater http://www.urec.fr/securite http://www.cru.fr/securite http://www.renater.fr ========================================================= + CERT-RENATER | tel : 01-53-94-20-44 + + 151 bd de l'Hopital | fax : 01-53-94-20-41 + + 75013 Paris | email: certsvp@renater.fr + =========================================================