----- Forwarded message from AIX Service Mail Server <aixservat_private> ----- This file contains security alerts published by the IBM Emergency Response Service. These alerts are published at the following URL on the world-wide web: http://www.ers.ibm.com/ In order to keep the size of this file reasonable, it contains only advisories for the current year. You can obtain a list of previous advisories either from the above URLs, or by requesting one of the "ERS_YYYY" documents from this mail server. The fixes mentioned in this document, when available, will be available from FixDist. Information on obtaining and using FixDist is available by requesting the 'FixDist' document from this mail server, or at the following URL on the world-wide web: http://techsupport.services.ibm.com/rs6k/fixes.html The 'Security_APARs' document on this mail server contains a list of security related APARs. =============================================================================== =============================================================================== VULNERABILITY SUMMARY VULNERABILITY: Root Shell Spawning Possible Via "diagrpt" PLATFORMS: IBM AIX 4.3.x and 5.1 SOLUTION: Apply the emergency-fixes described below, or employ the workaround, also described below. THREAT: Malicious user could obtain root privileges. CERT Advisory: NONE. =========================================================================== DETAILED INFORMATION I. Description AIX ships with the diagnostic reporting command, "diagrpt". This command is shipped SUID, or "set user ID", and is executable by an ordinary user. An ordinary user is able to set the "DIAGDATADIR" environment veriable to a directory of his or her choosing. In this directory, a user can place a carefully crafted shell program that is executed when the user runs the "diagrpt" command. The SUID bit for "diagrpt" will run the shell program as root, and this program will force the spawning of a new shell with root privileges. II. Impact A malicious local user can use a well-crafted exploit code to gain root privileges on the attacked system, compromising the integrity of the system and its attached local network. III. Solutions A. WORKAROUND If you do not wish to install the efix for this vulnerability but instead wait for the APAR that fixes it to be made available, you can also negate this vulnerability by making the "diagrpt" command to be non-SUID. You must be "root" to do this. However, ordinary users will not be able to use the command if the SUID bit is removed. B. Official fix IBM is working on the following fixes which will be available soon: AIX 4.3.x and 5.1: APAR assignment pending. NOTE: Fix will not be provided for versions prior to 4.3 as these are no longer supported by IBM. Affected customers are urged to upgrade to 4.3.3 at the latest maintenance level, or to 5.1. C. How to minimize the vulnerability Temporary fixes for AIX 4.3.x and 5.1 systems are available. The temporary fixes can be downloaded via ftp from: ftp://aix.software.ibm.com/aix/efixes/security/diagrpt_efix.tar.Z The efix tarball consists of two patched diagrpt tarred binaries, one for AIX 4.3.x systems (diagrpt.43.tar) and one for AIX 5.1 (diagrpt.51.tar). A copy of this Advisory is included in the efix tarball. These temporary fixes 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. To proceed with efix installation: First, verify the MD5 cryptographic hash sums of each efix files you obtain from unpacking the efix tarball with those given below. These should match exactly; if they do not, double check the hash results and the download site address. If OK, contact IBM AIX Security at security-alertat_private and describe the discrepancy. Filename sum md5 ================================================================= diagrpt.43.tar 02875 30 168c5bf253b516cd7e6a69a94aefa061 diagrpt.51.tar 02327 30 f5df8339dde46d3cc12c6d7b22fd37c4 Efix Installation Instructions: ------------------------------- IMPORTANT NOTICE: Before installing the efix, you must upgrade to the latest maintenance level of AIX for your version of AIX. For AIX 4.3, this level is 4.3.3.75. For AIX 5.1, this level is 5.1.0.0. 1. Become root, if not already done. 2. Change to the /usr/lpp/diagnostics/bin directory. Make a backup copy of the existing diagrpt binary, giving it a distinctive, meaningful name, such as "diagrpt.original" or "diagrpt.backup". This is IMPORTANT to do, so you can recover the orginal diagrpt binary if something goes wrong during the installation of the efix! 3. In the root ("/") directory, download, uncompress, and untar the efix. a. uncompress diagrpt_efix.tar.Z b. tar -xvf diagrpt_efix.tar 4. You will have two tarfiles: "diagrpt.43.tar" and "diagrpt.51.tar". Save the tarfile appropriate for your version of AIX (i.e., 4.3.3.x or 5.1.0.0); you may discard the other, unneeded tarfile. Untar the appropriate (for your AIX version) tarfile by executing "tar -xvf diagrpt.xy.tar". The efix version of diagrpt will be untarred and placed in the proper directory. "xy" is either "43" or "51". 5. Check to be certain that the new diagrpt is SUID and is assigned proper permissions, "-r-sr-xr-x", and the ownership is assigned properly, "root" and "system". IV. Obtaining Fixes IBM AIX APARs may be ordered using Electronic Fix Distribution (via the FixDist program), or from the IBM Support Center. For more information on FixDist, and to obtain fixes via the Internet, please reference http://techsupport.services.ibm.com/rs6k/fixes.html or send email to "aixservat_private" with the word "FixDist" in the "Subject:" line. To facilitate ease of ordering all security related APARs for each AIX release, security fixes are periodically bundled into a cumulative APAR. For more information on these cumulative APARs including last update and list of individual fixes, send email to "aixservat_private" with the word "subscribe Security_APARs" in the "Subject:" line. V. Acknowledgements Many thanks go to Johan Van Mengsel of IBM Belgium for discovering this vulnerability, and to Troy Bollinger of IBM Boulder and Austin for demonstrating the exploitation of this vulnerability. VI. Contact Information Comments regarding the content of this announcement can be directed to: security-alertat_private To request the PGP public key that can be used to encrypt new AIX security vulnerabilities, send email to security-alertat_private with a subject of "get key". If you would like to subscribe to the AIX security newsletter, send a note to aixservat_private with a subject of "subscribe Security". To cancel your subscription, use a subject of "unsubscribe Security". To see a list of other available subscriptions, use a subject of "help". IBM and AIX are a registered trademark of International Business Machines Corporation. All other trademarks are property of their respective holders. ----- End forwarded message -----
This archive was generated by hypermail 2b30 : Fri Jun 22 2001 - 16:02:30 PDT