__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Center ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Red Hat "at" Vulnerability [Red Hat RHSA-2002:015-17] March 18, 2002 22:00 GMT Number M-057 ______________________________________________________________________________ PROBLEM: A heap corruption vulnerability exists in the "at" program that allows local users to execute arbitrary code. PLATFORM: Red Hat Linux 6.2 - alpha, i386, sparc Red Hat Linux 7.0 - alpha, i386 Red Hat Linux 7.1 - alpha, i386, ia64 Red Hat Linux 7.2 - i386, ia64, s390 DAMAGE: A malicious local user could execute arbitrary code. The "at" command is installed as setuid root, therefore arbitrary code would be run with root privileges. SOLUTION: Apply the appropriate RPMs. ______________________________________________________________________________ VULNERABILITY The risk is LOW. A local user account is necessary to exploit ASSESSMENT: this vulnerability. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/m-057.shtml ORIGINAL BULLETIN: https://www.redhat.com/support/errata/RHSA-2002-015.html ______________________________________________________________________________ [***** Start Red Hat RHSA-2002:015-17 *****] ----------------------------------------------------------------------- Synopsis: Updated at package available ----------------------------------------------------------------------- Advisory ID: RHSA-2002:015-17 ----------------------------------------------------------------------- Issue Date: 2002-01-15 ----------------------------------------------------------------------- Updated On: 2002-03-13 ----------------------------------------------------------------------- Product: Red Hat Linux ----------------------------------------------------------------------- Keywords: at security heap corruption environment ----------------------------------------------------------------------- Cross References: ----------------------------------------------------------------------- Obsoletes: ----------------------------------------------------------------------- 1. Topic: This updated at package fixes two minor problems and one major problem where the environment can get wiped out prior to the execution of a scheduled command. For versions of Red Hat Linux prior to 7.2, this package also fixes a potential security vulnerability which can result in heap corruption (Red Hat Linux 7.2 is not vulnerable to this security exploit). Update 2002-02-01: The package for Red Hat Linux 6.2 tried to source a file in /etc/init.d, which doesn't exist on a standard system. 2. Problem description: A server running the latest version of at could have commands that depend on the current environment (for example, the PATH) which would then fail or run incorrectly because the environment would not be accessible when the command was executed at a later time. Additionally, in versions of Red Hat Linux prior to 7.2 a malicious local user could specify an execution time is in a carefully drafted format causing a heap corruption bug. Since the at command is installed as setuid root this bug can be exploited. The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name CAN-2002-0004 to this issue. Thanks to zen-parse for reporting this vulnerability. In addition to the fixed heap corruption, file handling security on all versions of at has been improved by adding the O_EXCL (exclusive) option to an open system call. 3. Bug IDs fixed: (see bugzilla for more information) 49491 - all environment is wiped out prior to executing user command 51253 - Wrong pointer to time syntax in man page 52626 - "at" RPM says that /var/spool/at/.SEQ should be executable 4. Relevant releases/architectures: Red Hat Linux 6.2 - alpha, i386, sparc Red Hat Linux 7.0 - alpha, i386 Red Hat Linux 7.1 - alpha, i386, ia64 Red Hat Linux 7.2 - i386, ia64, s390 5. RPMs required: Red Hat Linux 6.2: SRPMS: ftp://updates.redhat.com/6.2/en/os/SRPMS/at-3.1.8-22.2.src.rpm alpha: ftp://updates.redhat.com/6.2/en/os/alpha/at-3.1.8-22.2.alpha.rpm i386: ftp://updates.redhat.com/6.2/en/os/i386/at-3.1.8-22.2.i386.rpm sparc: ftp://updates.redhat.com/6.2/en/os/sparc/at-3.1.8-22.2.sparc.rpm Red Hat Linux 7.0: SRPMS: ftp://updates.redhat.com/7.0/en/os/SRPMS/at-3.1.8-23.src.rpm alpha: ftp://updates.redhat.com/7.0/en/os/alpha/at-3.1.8-23.alpha.rpm i386: ftp://updates.redhat.com/7.0/en/os/i386/at-3.1.8-23.i386.rpm Red Hat Linux 7.1: SRPMS: ftp://updates.redhat.com/7.1/en/os/SRPMS/at-3.1.8-23.src.rpm alpha: ftp://updates.redhat.com/7.1/en/os/alpha/at-3.1.8-23.alpha.rpm i386: ftp://updates.redhat.com/7.1/en/os/i386/at-3.1.8-23.i386.rpm ia64: ftp://updates.redhat.com/7.1/en/os/ia64/at-3.1.8-23.ia64.rpm Red Hat Linux 7.2: SRPMS: ftp://updates.redhat.com/7.2/en/os/SRPMS/at-3.1.8-23.src.rpm i386: ftp://updates.redhat.com/7.2/en/os/i386/at-3.1.8-23.i386.rpm ia64: ftp://updates.redhat.com/7.2/en/os/ia64/at-3.1.8-23.ia64.rpm s390: ftp://updates.redhat.com/7.2/en/os/s390/at-3.1.8-23.s390.rpm 6. Solution: Before applying this update, make sure all previously released errata relevant to your system have been applied. To update all RPMs for your particular architecture, run: rpm -Fvh [filenames] where [filenames] 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 directory *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. 7. Verification: MD5 sum Package Name ------------------------------------------------------------------------- beab8c80838d3920d758a2e8e5b5e3b2 6.2/en/os/SRPMS/at-3.1.8-22.2.src.rpm 31a1aac9c620778fe24a5d9c73b468c6 6.2/en/os/alpha/at-3.1.8-22.2.alpha.rpm a5ea88124398a0b937dd93e93d62c3bd 6.2/en/os/i386/at-3.1.8-22.2.i386.rpm 3ee8b5c53f23d0eae9bd78c69621ff78 6.2/en/os/sparc/at-3.1.8-22.2.sparc.rpm b1f62f4b41e12a54a1f73d639363a638 7.0/en/os/SRPMS/at-3.1.8-23.src.rpm 97e27a1d2dc0f08d8f118209a891689a 7.0/en/os/alpha/at-3.1.8-23.alpha.rpm ea793fd803f10c8fa66abb8191fefb9b 7.0/en/os/i386/at-3.1.8-23.i386.rpm b1f62f4b41e12a54a1f73d639363a638 7.1/en/os/SRPMS/at-3.1.8-23.src.rpm 97e27a1d2dc0f08d8f118209a891689a 7.1/en/os/alpha/at-3.1.8-23.alpha.rpm ea793fd803f10c8fa66abb8191fefb9b 7.1/en/os/i386/at-3.1.8-23.i386.rpm 8fed88d53824e98f509289c42ea01237 7.1/en/os/ia64/at-3.1.8-23.ia64.rpm b1f62f4b41e12a54a1f73d639363a638 7.2/en/os/SRPMS/at-3.1.8-23.src.rpm ea793fd803f10c8fa66abb8191fefb9b 7.2/en/os/i386/at-3.1.8-23.i386.rpm 8fed88d53824e98f509289c42ea01237 7.2/en/os/ia64/at-3.1.8-23.ia64.rpm b392c294aab8dfa5ec86255d7582fa04 7.2/en/os/s390/at-3.1.8-23.s390.rpm These packages are GPG signed by Red Hat, Inc. for security. Our key is available at: http://www.redhat.com/about/contact.html You can verify each package with the following command: rpm --checksig filename 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 filename Note that you need RPM >= 3.0 to check GnuPG keys. 8. References: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2002-0004 [***** End Red Hat RHSA-2002:015-17 *****] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Red Hat, Inc. for the information contained in this bulletin. _______________________________________________________________________________ CIAC, the Computer Incident Advisory Center, 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). 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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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