__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Red Hat Linux "vixie-cron buffer overflow username crontab" February 20, 2001 20:00 GMT Number L-048 ______________________________________________________________________________ PROBLEM: A buffer overflow flaw exists in the crontab file. PLATFORM: Red Hat Linux 5.2 - alpha, i386, sparc Red Hat Linux 6.2 - alpha, i386, sparc Red Hat Linux 7.0 - alpha, i386 DAMAGE: The crontab flaw could allow a local user to elevate their privileges, leading to a possible root compromise. SOLUTION: All users are advised to update their RPM files, as outlined in the advisory. ______________________________________________________________________________ VULNERABILITY The risk is MEDIUM. This issue has been discussed in public ASSESSMENT: forums. ______________________________________________________________________________ [****** Begin Red Hat Advisory ******] --------------------------------------------------------------------- Red Hat, Inc. Red Hat Security Advisory Synopsis: New vixie-cron packages available Advisory ID: RHSA-2001:014-03 Issue date: 2001-02-12 Updated on: 2001-02-19 Product: Red Hat Linux Keywords: vixie-cron buffer overflow username crontab Cross references: Obsoletes: --------------------------------------------------------------------- 1. Topic: New vixie-cron packages are available that fix a buffer overflow in the 'crontab' command; this could allow certain users to gain elevated privileges. It is recommended that all users update to the fixed packages. Users of Red Hat Linux 6.0 or 6.1 should use the packages for Red Hat Linux 6.2. 2. Relevant releases/architectures: Red Hat Linux 5.2 - alpha, i386, sparc Red Hat Linux 6.2 - alpha, i386, sparc Red Hat Linux 7.0 - alpha, i386 3. Problem description: A buffer overflow existed in the 'crontab' command; if called by a user with a username longer than 20 characters. If the system administrator has created usernames of that length, it would be possible for those users to gain elevated privileges. 4. Solution: To update all RPMs for your particular architecture, run: rpm -Fvh where is a list of the RPMs you wish to upgrade. Only those RPMs which are currently installed will be updated. Those RPMs which are not installed but included in the list will not be updated. Note that you can also use wildcards (*.rpm) if your current directly *only* contains the desired RPMs. Please note that this update is also available via Red Hat Network. Many people find this an easier way to apply updates. To use Red Hat Network, launch the Red Hat Update Agent with the following command: up2date This will start an interactive process that will result in the appropriate RPMs being upgraded on your system. 5. Bug IDs fixed (http://bugzilla.redhat.com/bugzilla for more info): 6. RPMs required: Red Hat Linux 5.2: SRPMS: ftp://updates.redhat.com/5.2/SRPMS/vixie-cron-3.0.1-38.5.2.src.rpm alpha: ftp://updates.redhat.com/5.2/alpha/vixie-cron-3.0.1-38.5.2.alpha.rpm i386: ftp://updates.redhat.com/5.2/i386/vixie-cron-3.0.1-38.5.2.i386.rpm sparc: ftp://updates.redhat.com/5.2/sparc/vixie-cron-3.0.1-38.5.2.sparc.rpm Red Hat Linux 6.2: SRPMS: ftp://updates.redhat.com/6.2/SRPMS/vixie-cron-3.0.1-40.1.src.rpm alpha: ftp://updates.redhat.com/6.2/alpha/vixie-cron-3.0.1-40.1.alpha.rpm i386: ftp://updates.redhat.com/6.2/i386/vixie-cron-3.0.1-40.1.i386.rpm sparc: ftp://updates.redhat.com/6.2/sparc/vixie-cron-3.0.1-40.1.sparc.rpm Red Hat Linux 7.0: SRPMS: ftp://updates.redhat.com/7.0/SRPMS/vixie-cron-3.0.1-61.src.rpm alpha: ftp://updates.redhat.com/7.0/alpha/vixie-cron-3.0.1-61.alpha.rpm i386: ftp://updates.redhat.com/7.0/i386/vixie-cron-3.0.1-61.i386.rpm 7. Verification: MD5 sum Package Name -------------------------------------------------------------------------- 3a89bffb76e4f6aa4b2f2642ba043bc7 5.2/SRPMS/vixie-cron-3.0.1-38.5.2.src.rpm 4ba62d6f55d8bbeb47e57b0a9464701b 5.2/alpha/vixie-cron-3.0.1-38.5.2.alpha.rpm 5827b0be32d899fdad229e225cbd4782 5.2/i386/vixie-cron-3.0.1-38.5.2.i386.rpm 73906a21d198cbf255c724fab8de9a21 5.2/sparc/vixie-cron-3.0.1-38.5.2.sparc.rpm e037d33b2c605b054308b543613c9b52 6.2/SRPMS/vixie-cron-3.0.1-40.1.src.rpm e0ab2bc7b094d65971a3acae39379e20 6.2/alpha/vixie-cron-3.0.1-40.1.alpha.rpm 12d0cc89ca909ac56774e136af0442b5 6.2/i386/vixie-cron-3.0.1-40.1.i386.rpm 4b9249539b22b0671577d738b64c4d58 6.2/sparc/vixie-cron-3.0.1-40.1.sparc.rpm 16fbd0ee65609ab35c96699089604870 7.0/SRPMS/vixie-cron-3.0.1-61.src.rpm b0cfceed1c6d1df1229f434d7adec14d 7.0/alpha/vixie-cron-3.0.1-61.alpha.rpm 13707ef913e7801da32f9d47a419f81b 7.0/i386/vixie-cron-3.0.1-61.i386.rpm These packages are GPG signed by Red Hat, Inc. for security. Our key is available at: http://www.redhat.com/corp/contact.html You can verify each package with the following command: rpm --checksig If you only wish to verify that each package has not been corrupted or tampered with, examine only the md5sum with the following command: rpm --checksig --nogpg 8. References: Copyright(c) 2000, 2001 Red Hat, Inc. [****** End Red Hat Advisory ******] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Red Hat, Inc. 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. 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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. 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