MCI Telecommunications internetMCI Security Group Report Name: iMCI MIIGS Security Alert Report Number: iMCISE:IMCICIAC:083196:01:P1R1 Report Date: 08/31/96 Report Format: Formal Report Classification: MCI Informational Report Reference: http://www.security.mci.net Report Distribution: iMCI Security, MCI Internal Internet Gateway Security (MIIGS), MCI Emergency Alert LiSt (MEALS) (names on file) ------------------------------------------------------------------------------- -----BEGIN PGP SIGNED MESSAGE----- __________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Vulnerability in WorkMan Program August 29, 1996 15:00 GMT Number G-42 ______________________________________________________________________________ PROBLEM: When the "WorkMan" compact disc playing program is installed set-user-id "root", it can be used to make any file on the system world-writable. PLATFORM: Linux, UNIX System V Release 4.0 (and derivatives). DAMAGE: A non-privileged user can use "WorkMan" to make any file on the system world-writable, and then modify that file's contents. This vulnerbility can allow the user to create accounts, destroy log files, and perform other unauthorized actions. SOLUTION: Apply the patches listed in the vendor bulletin below. ______________________________________________________________________________ VULNERABILITY This vulnerability is becoming widely known. ASSESSMENT: ______________________________________________________________________________ [Begin IBM Bulletin] - - --ERS-ALERT--ERS-ALERT--ERS-ALERT--ERS-ALERT--ERS-ALERT--ERS-ALERT-ERS-ALERT - - ---EXTERNAL RELEASE---EXTERNAL RELEASE---EXTERNAL RELEASE---EXTERNAL RELEASE ======= ============ ====== ====== ======= ============== ======= ======= === === ==== ====== ====== === =========== ======= ======= === =========== === ======= === === === ==== === ===== === ======= ============== ===== === ===== ======= ============ ===== = ===== EMERGENCY RESPONSE SERVICE SECURITY VULNERABILITY ALERT 28 August 1996 18:00 GMT Number: ERS-SVA-E01-1996:005.1 ============================================================================= VULNERABILITY SUMMARY VULNERABILITY: When the "WorkMan" compact disc playing program is installed set-user-id "root," it can be used to make any file on the system world-writable. PLATFORMS: Linux, UNIX System V Release 4.0 (and derivatives) SOLUTION: Remove the set-user-id bit from the "workman" program. THREAT: A non-privileged user can use "WorkMan" to make any file on the system world-writable, and then modify that file's contents. ============================================================================= DETAILED INFORMATION NOTE: This advisory is NOT a re-hash of the problem reported on several lists earlier this week by a group calling itself "r00t." The vulnerability described by "r00t" is essentially a subset of the problem described in this alert. I. Description "WorkMan" is a popular program used for playing audio compact disks on local workstation CD-ROM drives that is widely available from many sites around the Internet. Versions of "WorkMan" are also included with some operating system distributions, such as Linux. On systems where "WorkMan" was built and installed using the procedures that are given in "Makefile.linux" or "Makefile.svr4" (in general, this means on Linux systems and UNIX System V Release 4.0 systems), the "workman" program is installed set-user-id "root." This means that when the program is run, it will execute with super-user permissions. In order to allow signals to be sent to it, "WorkMan" writes its process-id to a file called "/tmp/.wm_pid." The "-p" option to the program allows the user to specify a different file name in which to record this information. When a file is specified with "-p", "WorkMan" simply attempts to create and/or truncate the file, and if this succeeds, "WorkMan" changes the permissions on the file so that it is world-readable and world-writable. In the general case, when "WorkMan" is installed without the set-user-id bit set, the normal file access permissions provided by the operating system will prevent users from creating or truncating files they are not authorized to create or truncate. However, when "WorkMan" is installed set-user-id "root," this process breaks down (because "root" is allowed to create/truncate any file). II. Impact A user executing a set-user-id "root" version of "WorkMan" can use the "-p" option to create a file anywhere in the file system, or to truncate any file in the file system. More importantly, the file specified with "-p" will be world-readable and world-writable when "WorkMan" is finished. This can enable the user to create accounts, destroy log files, and perform other unauthorized actions. III. Solutions "WorkMan" does not require the set-user-id bit to work; it is installed this way only on systems that do not make the CD-ROM device file world-readable by default. This vulnerability can be alleviated by: 1) Removing the set-user-id bit from the "WorkMan" program, via a command such as chmod u-s /usr/local/bin/workman and 2) Making the CD-ROM device world-readable, via a command such as chmod +r /dev/cdrom Note that on multi-user systems, part (2) of the above procedure will allow any user to access the contents of the disc installed in the CD-ROM; this may not be desirable in all environments. IV. Acknowledgements IBM-ERS would like to thank the IBM Global Security Analysis Laboratory at the IBM T. J. Watson Research Center for their discovery of this vulnerability, bringing it to our attention, providing the steps to fix it, and assistance in developing this alert. UNIX is a technology trademark of X/Open Company, Ltd. =============================================================================== [End IBM Bulletin] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of IBM 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: +1 510-422-8193 FAX: +1 510-423-8002 STU-III: +1 510-423-2604 E-mail: ciac@llnl.gov For emergencies and off-hour assistance, DOE, DOE contractor sites, and the NIH may contact CIAC 24-hours a day. During off hours (5PM - 8AM PST), call the CIAC voice number 510-422-8193 and leave a message, or call 800-759-7243 (800-SKY-PAGE) to send a Sky Page. CIAC has two Sky Page PIN numbers, the primary PIN number, 8550070, is for the CIAC duty person, and the secondary PIN number, 8550074 is for the CIAC Project Leader. Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://ciac.llnl.gov/ Anonymous FTP: ciac.llnl.gov (128.115.19.53) Modem access: +1 (510) 423-4753 (28.8K baud) +1 (510) 423-3331 (28.8K baud) CIAC has several self-subscribing mailing lists for electronic publications: 1. CIAC-BULLETIN for Advisories, highest priority - time critical information and Bulletins, important computer security information; 2. CIAC-NOTES for Notes, a collection of computer security articles; 3. SPI-ANNOUNCE for official news about Security Profile Inspector (SPI) software updates, new features, distribution and availability; 4. SPI-NOTES, for discussion of problems and solutions regarding the use of SPI products. Our mailing lists are managed by a public domain software package called ListProcessor, which ignores E-mail header subject lines. To subscribe (add yourself) to one of our mailing lists, send the following request as the E-mail message body, substituting CIAC-BULLETIN, CIAC-NOTES, SPI-ANNOUNCE or SPI-NOTES for list-name and valid information for LastName FirstName and PhoneNumber when sending E-mail to ciac-listproc@llnl.gov: subscribe list-name LastName, FirstName PhoneNumber e.g., subscribe ciac-notes OHara, Scarlett W. 404-555-1212 x36 You will receive an acknowledgment containing address, initial PIN, and information on how to change either of them, cancel your subscription, or get help. 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 by sending email to docserver@first.org with an empty subject line and a message body containing the line: send first-contacts. 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. LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC) G-32: HP-UX Vulnerabilities in expreserve, rpc.pcnfsd, rpc.statd G-33: rdist vulnerability G-34: HP-UX Vulnerabilities (netttune, SAM remote admin) G-35: SUN Microsystems Solaris vold Vulnerability G-36: HP-UX Vulnerabilities in elm and rdist Programs G-37: Vulnerability in Adobe FrameMaker (fm_fls) G-38: Linux Vulnerabilities in mount and umount Programs G-39: Vulnerability in expreserve G-40: SGI admin and user Program Vulnerabilities G-41: Vulnerability in BASH Program RECENT CIAC NOTES ISSUED (Previous Notes available from CIAC) Notes 07 - 3/29/95 A comprehensive review of SATAN Notes 08 - 4/4/95 A Courtney update Notes 09 - 4/24/95 More on the "Good Times" virus urban legend Notes 10 - 6/16/95 PKZ300B Trojan, Logdaemon/FreeBSD, vulnerability in S/Key, EBOLA Virus Hoax, and Caibua Virus Notes 11 - 7/31/95 Virus Update, Hats Off to Administrators, America On-Line Virus Scare, SPI 3.2.2 Released, The Die_Hard Virus Notes 12 - 9/12/95 Securely configuring Public Telnet Services, X Windows, beta release of Merlin, Microsoft Word Macro Viruses, Allegations of Inappropriate Data Collection in Win95 Notes 96-01 - 3/18/96 Java and JavaScript Vulnerabilities, FIRST Conference Announcement, Security and Web Search Engines, Microsoft Word Macro Virus Update -----BEGIN PGP SIGNATURE----- Version: 4.0 Business Edition iQCVAgUBMicE47nzJzdsy3QZAQGRCQQAiA9WGkaF14qx8/7X3qvEicuv23dBgrlV siE/Jcq7yBMtuDCThMk9nDbDf1fGLUyysZ/MeeS9ybBpWJxzgWL2iXP9f0yBRtap siGX0ij+7LKrexR5nWBsdf7jZF34qaqU8xRlBHxbC7QiZIZD7SMtl9ZYBsflN8nP CFT0bTnpUOk= =PYbw -----END PGP SIGNATURE----- ===============================================================