__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN IBM AIX rexecd Vulnerability [MSS-OAR-E01-2004:0303.1] March 18, 2004 19:00 GMT Number O-102 ______________________________________________________________________________ PROBLEM: A vulnerability was discovered in the rexecd daemon. rexecd ships as part of the bos.net.tcp.client fileset. PLATFORM: AIX 4.3.3 DAMAGE: This vulnerability can cause user information of the connecting user to potentially be overwritten with that of another user. The connection would proceed with the overwritten data and the connecting user would then have the privileges of the other user. This may be dependent on the type of authentication defined for the connecting user. It is possible, but not certain, that the connecting user may gain root privileges. SOLUTION: Install the appropriate upgrade. ______________________________________________________________________________ VULNERABILITY The risk is MEDIUM. It is possible that the connecting user may ASSESSMENT: gain root privileges. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/o-102.shtml ORIGINAL BULLETIN: IBM Security Advisory MSS-OAR-E01-2004:0303.1 http://www-1.ibm.com/services/continuity/recover1.nsf/mss /MSS-OAR-E01-2004.0303.1 ______________________________________________________________________________ [***** Start MSS-OAR-E01-2004:0303.1 *****] IBM SECURITY ADVISORY First Issued: Mon Mar 8 09:43:27 CST 2004 =========================================================================== VULNERABILITY SUMMARY VULNERABILITY: Vulnerability in rexecd may allow root access PLATFORMS: AIX 4.3.3 SOLUTION: Apply the APAR listed below. THREAT: A remote attacker may gain root privileges. CERT VU Number: n/a CVE Number: n/a =========================================================================== DETAILED INFORMATION I. Description =============== A vulnerability was discovered in the rexecd daemon that may allow remote user to gain root privileges. This vulnerability can cause user information of the connecting user to be potentially be overwritten with that of another user. The connection would proceed with the overwritten data and the connecting user would then have the privileges of the other user. This may be dependent on the type of authentication defined for the connecting user. It is possible, but not certain, that the connecting user may gain root privileges. Note that this only applies to AIX 4.3.3. rexecd ships as part of the bos.net.tcp.client fileset. To determine if this fileset is installed, execute the following command: # lslpp -L bos.net.tcp.client This vulnerability is in filesets 4.3.3.91 and below. II. Impact ========== A remote attacker may gain root privileges. III. Solutions =============== A. Official Fix IBM provides the following fixes: APAR number for AIX 4.3.3: IY53507 NOTE: Affected customers are urged to upgrade to 5.1.0 or 5.2.0 at the latest maintenance level. B. Workaround The rexec daemon runs under the control of the inetd daemon. To disable the rexecd daemon, as root enter: # smitty rminetdconf Scan through the list of subservers. If rexecd is not listed it is not enabled. If it is listed, place the cursor on the name and press enter. To make the change effective enter: # refresh -s inetd IV. Obtaining Fixes =================== AIX Version 4.3.3 and 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. Acknowledgements =================== This document written by Kent Stuiber. VI. 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. 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[***** End MSS-OAR-E01-2004:0303.1 *****] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of IBM Global Services Managed Security Services for the information contained in this bulletin. _______________________________________________________________________________ CIAC, the Computer Incident Advisory Capability, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. CIAC is also a founding member of FIRST, the Forum of Incident Response and Security Teams, a global organization established to foster cooperation and coordination among computer security teams worldwide. CIAC services are available to DOE, DOE contractors, and the NIH. CIAC can be contacted at: Voice: +1 925-422-8193 (7x24) FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: ciac@ciac.org Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ Anonymous FTP: ftp.ciac.org PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Your agency's team will coordinate with CIAC. The Forum of Incident Response and Security Teams (FIRST) is a world-wide organization. A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. 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