-----BEGIN PGP SIGNED MESSAGE----- - ---EXTERNAL RELEASE---EXTERNAL RELEASE---EXTERNAL RELEASE---EXTERNAL RELEASE--- ======= ============ ====== ====== ======= ============== ======= ======= === === ==== ====== ====== === =========== ======= ======= === =========== === ======= === === === ==== === ===== === ======= ============== ===== === ===== ======= ============ ===== = ===== EMERGENCY RESPONSE SERVICE OUTSIDE ADVISORY REDISTRIBUTION 17 July 1996 18:00 GMT Number: ERS-OAR-E01-1996:003.1 =============================================================================== The IBM-ERS Outside Advisory Redistribution is designed to provide customers of the IBM Emergency Response Service with access to the security advisories sent out by other computer security incident response teams, vendors, and other groups concerned about security. IBM makes no representations and assumes no responsibility for the contents or accuracy of the advisories themselves. IBM-ERS is forwarding the following information from FreeBSD, Inc.. Contact information for FreeBSD, Inc. is included in the forwarded text below; please contact them if you have any questions or need further information. =============================================================================== ********************** FORWARDED INFORMATION STARTS HERE ********************** ============================================================================= FreeBSD-SA-96:16 Security Advisory Revised: Fri Jul 12 09:32:53 PDT 1996 FreeBSD, Inc. Topic: security vulnerability in rdist Category: core Module: rdist Announced: 1996-07-12 Affects: FreeBSD 2.0, 2.0.5, 2.1, 2.1-stable, and 2.2-current Corrected: 2.1-stable and 2.2-current as of 1996-07-11 Source: 4.4BSD (lite) FreeBSD only: no Patches: ftp://freebsd.org/pub/CERT/patches/SA-96:16/ Reference: [8lgm]-Advisory-26.UNIX.rdist.20-3-1996 ============================================================================= I. Background A bug was found in the BSD rdist utility which can allow an unprivileged local user to gain unauthorized access. This problem is present in all source code and binary distributions of FreeBSD version 2.x released before 1996-07-12. rdist has been the subject of security vulnerabilities in the past. This is a newly discovered vulnerability not related to previous race conditions fixed in rdist. II. Problem Description rdist creates an error message based on a user provided string, without checking bounds on the buffer used. This buffer is on the stack, and can therefore be used to execute arbitrary instructions. III. Impact This vulnerability can allow a local user to obtain superuser privileges. It may only be exploited by users with a valid account on the local system. It is present in almost all BSD derived operating systems with a "setuid" rdist program. IV. Workaround The rdist program must be setuid root to function properly. This vulnerability can be eliminated by making rdist not executable by unprivileged users. Since this limits the usefulness of the program, a software update is advised. This workaround will work for all versions of FreeBSD affected by this problem. As root, execute the commands: # chflags noschg /usr/bin/rdist # chmod u-s,go-rx /usr/bin/rdist then verify that the setuid permissions of the files have been removed. The permissions array should read "-r-x------" as shown here: # ls -l /usr/bin/rdist -r-x------ 1 root bin 49152 Jun 16 10:46 rdist V. Solution(s) Apply the available via FTP from the patch directory noted at the top of this message. Recompile, and reinstall the rdist program. This patch is known to apply to all FreeBSD 2.x systems, it has not been tested with FreeBSD 1.x. The [8lgm] organization correctly points out that this program does not have a particularly good security "history." While the patch for this vulnerability does solve this particular problem, it's not clear if other security issues involving rdist will appear in the future. Administrators should consider whether it is appropriate to remove the standard rdist program and upgrade to rdist version 6, which is available as a FreeBSD port. FreeBSD, Inc. has not replaced the standard BSD rdist with the newer code because the new rdist is not protocol-compatible with the original version. ============================================================================= FreeBSD, Inc. Web Site: http://www.freebsd.org/ Confidential contacts: security-officer@freebsd.org PGP Key: ftp://freebsd.org/pub/CERT/public_key.asc Security notifications: security-notifications@freebsd.org Security public discussion: security@freebsd.org Notice: Any patches in this document may not apply cleanly due to modifications caused by digital signature or mailer software. Please reference the URL listed at the top of this document for original copies of all patches if necessary. ============================================================================= *********************** FORWARDED INFORMATION ENDS HERE *********************** =============================================================================== IBM's Internet Emergency Response Service (IBM-ERS) is a subscription-based Internet security response service that includes computer security incident response and management, regular electronic verification of your Internet gateway(s), and security vulnerability alerts similar to this one that are tailored to your specific computing environment. By acting as an extension of your own internal security staff, IBM-ERS's team of Internet security experts helps you quickly detect and respond to attacks and exposures across your Internet connection(s). As a part of IBM's Business Recovery Services organization, the IBM Internet Emergency Response Service is a component of IBM's SecureWay(tm) line of security products and services. From hardware to software to consulting, SecureWay solutions can give you the assurance and expertise you need to protect your valuable business resources. To find out more about the IBM Internet Emergency Response Service, send an electronic mail message to ers-sales@vnet.ibm.com, or call 1-800-742-2493 (Prompt 4). IBM-ERS maintains a site on the World Wide Web at http://www.ers.ibm.com/. Visit the site for information about the service, copies of security alerts, team contact information, and other items. IBM-ERS uses Pretty Good Privacy* (PGP*) as the digital signature mechanism for security vulnerability alerts and other distributed information. The IBM-ERS PGP* public key is available from http://www.ers.ibm.com/team-info/pgpkey.html. "Pretty Good Privacy" and "PGP" are trademarks of Philip Zimmerman. IBM-ERS is a Member Team of the Forum of Incident Response and Security Teams (FIRST), a global organization established to foster cooperation and response coordination among computer security teams worldwide. The information in this document is provided as a service to customers of the IBM Emergency Response Service. Neither International Business Machines Corporation, Integrated Systems Solutions Corporation, 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 contained herein, or represents that its use would not infringe any 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 IBM or its subsidiaries. The views and opinions of authors expressed herein do not necessarily state or reflect those of IBM or its subsidiaries, and may not be used for advertising or product endorsement purposes. - ---EXTERNAL RELEASE---EXTERNAL RELEASE---EXTERNAL RELEASE---EXTERNAL RELEASE--- -----BEGIN PGP SIGNATURE----- Version: 2.7.1 iQCVAwUBMe1AkvWDLGpfj4rlAQHNqAP9GqBrDgSEV/mlMIJGrGJfXkGc7tb3qJOm wWMtmwDPNm/riyWiKCDAbpTox/iIAKRy7N4VfQ3/anZ7vXsBTHHdN+OaO4CSZrG4 EMUF/RvrrvFTjMoCFwwV/mf7GS/Bg8wAmp6vwL9242XfoyMyWvE/tAPpc5UBXpv8 e0uybiOtAQk= =4mZa -----END PGP SIGNATURE-----