===================================================================== CERT-Renater Note d'Information No. 2010/VULN327 _____________________________________________________________________ DATE : 30/08/2010 HARDWARE PLATFORM(S) : / OPERATING SYSTEM(S) : IBM AIX versions running AIX ftpd. ====================================================================== http://aix.software.ibm.com/aix/efixes/security/ftpd_advisory.asc ______________________________________________________________________ IBM SECURITY ADVISORY First Issued: Wed Aug 25 15:51:53 CDT 2010 The most recent version of this document is available here: http://aix.software.ibm.com/aix/efixes/security/ftpd_advisory.asc VULNERABILITY SUMMARY VULNERABILITY: AIX ftpd buffer overflow vulnerability PLATFORMS: AIX 5.3, and earlier releases SOLUTION: Apply the fix or workaround as described below. THREAT: A remote attacker may be able to execute arbirary code on a vulnerable server. CERT VU Number: n/a CVE Number: n/a Reboot required? NO Workarounds? YES Protected by FPM? NO Protected by SED? NO DETAILED INFORMATION I. DESCRIPTION There is a buffer overflow vulnerability in the ftp server. By issuing an overly long NLST command, an attacker may cause a buffer overflow. The successful exploitation of this vulnerability allows a remote attacker to get the DES encrypted user hashes off the server if FTP is configured to allow write access using Anonymous account or another account that is available to the attacker. The following executable is vulnerable: /usr/sbin/ftpd Please see the following for more information: http://www.exploit-db.com/exploits/14456/ II. PLATFORM VULNERABILITY ASSESSMENT Note: To use the following commands on VIOS you must first execute: oem_setup_env To determine if your system is vulnerable, execute the following command: lslpp -L bos.net.tcp.client The following fileset levels are vulnerable: AIX Fileset Lower Level Upper Level ------------------------------------------------ bos.net.tcp.client 5.3.9.0 5.3.9.9 bos.net.tcp.client 5.3.10.0 5.3.10.4 bos.net.tcp.client 5.3.11.0 5.3.11.4 bos.net.tcp.client 5.3.12.0 5.3.12.1 III. SOLUTION A. FIXES Fixes are now available. The fixes can be downloaded from: http://aix.software.ibm.com/aix/efixes/security/ftpd_fix.tar The links above are to a tar file containing this signed advisory, fix packages, and PGP signatures for each package. AIX Level VIOS Level Fix ------------------------------------------------------ 5.3.9 IZ83252_09.100824.epkg.Z 5.3.10 IZ83274_10.100824.epkg.Z 5.3.11 IZ83275_11.100824.epkg.Z 5.3.12 IZ83276_12.100824.epkg.Z To extract the fixes from the tar file: tar xvf qoslist_fix.tar cd qoslist_fix Verify you have retrieved the fixes intact: The checksums below were generated using the "csum -h SHA1" (sha1sum) commands and are as follows: csum -h SHA1 (sha1sum) filename ------------------------------------------------------------------ eebecb166c86462ce5ae150fa60a82dc08cfccda IZ83252_09.100824.epkg.Z 4598a4079cfe45b545c7d1d96dacbf4dda1b486e IZ83274_10.100824.epkg.Z 916fc41925d77c31478af8bd80e417d020fc6037 IZ83275_11.100824.epkg.Z 99117134e3cda009c6e19f5f334210e1a5ac4bab IZ83276_12.100824.epkg.Z To verify the sums, use the text of this advisory as input to csum or sha1sum. For example: csum -h SHA1 -i ftpd_advisory.asc sha1sum -c ftpd_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 and describe the discrepancy at the following addresses: security-alert@austin.ibm.com B. 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. Fix management documentation can be found at: http://www14.software.ibm.com/webapp/set2/sas/f/aix.efixmgmt/home.html To preview fix installation: emgr -e fix_name -p # where fix_name is the name of the # fix being previewed. To install fix package: emgr -e fix_name -X # where fix_name is the name of the # fix being installed. C. APARS IBM has assigned the following APARs to this problem: AIX Level APAR number Service pack date -------------------------------------------------------- 5.3.9 IZ83252 tbd 5.3.10 IZ83274 tbd 5.3.11 IZ83275 tbd 5.3.12 IZ83276 tbd Subscribe to the APARs here: http://www.ibm.com/support/docview.wss?uid=isg1IZ83252 http://www.ibm.com/support/docview.wss?uid=isg1IZ83274 http://www.ibm.com/support/docview.wss?uid=isg1IZ83275 http://www.ibm.com/support/docview.wss?uid=isg1IZ83276 By subscribing, you will receive periodic email alerting you to the status of the APAR, and a link to download the service pack when it becomes available. IV. WORKAROUND Configure ftp daemon to disallow write access to anonymous FTP users will limit the ability to create a directory that can trigger this vulnerability. VI. CONTACT INFORMATION If you would like to receive AIX Security Advisories via email, please visit: http://www.ibm.com/systems/support and click on the "My notifications" link. To view previously issued advisories, 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 obtain 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 our web page: http://www.ibm.com/systems/resources/systems_p_os_aix_security_pgpkey.txt C. Download the key from a PGP Public Key Server. The key ID is: 0x28BFAA12 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 This vulnerability was publicly disclosed by Kingcope. ====================================================================== ========================================================= 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 + =========================================================