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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2006.0225 -- [AIX] A race condition in sendmail may allow a remote attacker to execute arbitrary code. 23 March 2006 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: sendmail Publisher: IBM Operating System: AIX 5.1, 5.2 and 5.3 Impact: Execute Arbitrary Code/Commands Access: Remote/Unauthenticated CVE Names: CVE-2006-0058 Ref: AL-2006-0020 - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 IBM SECURITY ADVISORY First Issued: Tue Mar 22 10:00:00 CST 2006 ========================================================================== VULNERABILITY SUMMARY VULNERABILITY: A race condition in sendmail may allow a remote attacker to execute arbitrary code. PLATFORMS: AIX 5.1, 5.2 and 5.3. SOLUTION: Apply the APAR, interim fix or workaround as described below. THREAT: A remote user may execute arbitrary code. CERT VU Number: CVE-2006-0058 CVE Number: VU#834865 ========================================================================= DETAILED INFORMATION I. Description =============== A vulnerability was discovered in sendmail that may allow a remote attacker to execute arbitrary code. This vulnerability is caused by a race condition that occurs when handling asynchronous signals. Sendmail is a Mail Transfer Agent that ships with the AIX operating system. It is used for routing mail for local and network delivery. IBM is providing patches that remove possible attack vectors for this vulnerability. These patches should be installed as a precautionary measure. sendmail ships as part of the bos.net.tcp.client fileset. II. Impact ========== A remote attacker may execute arbitrary code with the privileges of the sendmail daemon. By default, sendmail runs with the privileges of the root user. III. Solutions =============== A. Official Fix IBM provides the following fixes: APAR number for AIX 5.1.0: IY82992 (available approx. 07/19/06) APAR number for AIX 5.2.0: IY82993 (available approx. 04/26/06) APAR number for AIX 5.3.0: IY82994 (available approx. 05/10/06) NOTE: Affected customers are urged to upgrade to the latest applicable Technology Level. B. Interim Fix Interim fixes are available. The ifixes can be downloaded via ftp from: ftp://aix.software.ibm.com/aix/efixes/security/sendmail_vu834865.tar.Z sendmail_vu834865.tar.Z is a compressed tarball containing this advisory, ifix packages and cleartext PGP signatures for each ifix package. Verify you have retrieved the fixes intact: +------------------------------------------ The interim fixes below are named by using the APAR corresponding to the release that the fix applies to. The APAR is followed by an underscore and the Technology Level for the particular AIX release that a fix applies to. The checksums below were generated using the "sum" and "md5sum" commands and are as follows: Filename sum md5 ======================================================================== IY82992_08.060321.epkg.Z 59022 595 058eae0dfb99d308b6ed682a68e59e23 IY82993_06.060321.epkg.Z 35133 568 171976668510c964aba539601b44d0f2 IY82993_07.060321.epkg.Z 47448 567 ffcdb1d2ade3fd459f7678823100f711 IY82993_08.060321.epkg.Z 01145 568 b2f2828da16b74169dff8c8155e3acda IY82994_02.060321.epkg.Z 22619 586 2f11241dfc1f1c063491464d64e9c310 IY82994_03.060321.epkg.Z 07719 587 a3bd5bba0a79de02f95debc3916c1fcd IY82994_04.060321.epkg.Z 44300 588 d310de002540a42dd9b816acf0bc40fc 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 ifixes have not been fully regression tested; thus, IBM does not warrant the fully correct functioning of the ifix. Customers install the ifix and operate the modified version of AIX at their own risk. Interim Installation Instructions: +--------------------------------- These packages use the new Interim Fix Management Solution to install and manage ifixes. More information can be found at: http://www14.software.ibm.com/webapp/set2/sas/f/aix.efixmgmt/home.html Stop sendmail. This can be done by executing the following command: # stopsrc -s sendmail To preview an epkg ifix installation execute the following command: # emgr -e ipkg_name -p # where ipkg_name is the name of the # ifix package being previewed. To install an epkg ifix package, execute the following command: # emgr -e ipkg_name -X # where ipkg_name is the name of the # ifix package being installed. The "X" flag will expand any filesystems if required. Start sendmail. This can be done by executing the following command: # startsrc -s sendmail -a "-bd -q30m" Verify that sendmail was started: # lssrc -s sendmail Subsystem Group PID Status sendmail mail 16000 active C. Workaround Turn sendmail off +---------------- If sendmail is not needed, turn it off. This can be done by using the stopsrc command: # stopsrc -s sendmail Verify that sendmail is no longer running: # lssrc -s sendmail Subsystem Group PID Status sendmail mail inoperative To prevent sendmail from starting on boot, edit the /etc/rc.tcpip startup script. Modify sendmail.cf +---------------- Setting LogLevel to 1 in /etc/sendmail.cf will eliminate some attack vectors for this vulnerability. IV. 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 V. 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 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 0x9391C1F2. 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. - -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) iD8DBQFEIWs6xwSSvpORwfIRArWNAJ9Xp3BnjCsd+c+D8Fe9BpZzptVHTgCfT18G YKusLNfGoSe94V1ZGz+H/rE= =oDtI - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. 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Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/render.html?cid=1980 If you believe that your computer system has been compromised or attacked in any way, we encourage you to let us know by completing the secure National IT Incident Reporting Form at: http://www.auscert.org.au/render.html?it=3192 =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQCVAwUBRCHwbih9+71yA2DNAQJ1hgP/aspXeGwKzbY5d+bNSufUYLzpgx592d28 fkprII0tsjFKcnhwbW+qlsJFkmza3hVW4H/IQ97jrvmLq4ZHJP6j3SaBDV86lY2F 43Mi3XbLu9Q1Q5uiM7CS0tvBnq2VIzwIehQ62jwSiQjqautdIPA8YSvImSCIMRQR tfljf1RFEVQ= =u8K/ -----END PGP SIGNATURE-----