__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN MIT krb5 Buffer overrun and underrun in Principal Name Handling [MIT krb5 Security Advisory 2003-005] March 20, 2003 22:00 GMT Number N-062 [REVISED 12 Nov 2003] ______________________________________________________________________________ PROBLEM: Buffer overrun and underrun problems exist in Kerberos principal name handling in unusual cases, such as names with zero components, names with one empty component, or host-based service principal names with no host name component. PLATFORM: MIT Kerberos 5, all released versions though 1.2.7 and 1.3-alpha1. DAMAGE: Corruption of malloc pool, probably leading to program crash. SOLUTION: Apply patch as stated in MIT's security bulletin. ______________________________________________________________________________ VULNERABILITY The risk is MEDIUM. Although this is a Denial-of-Service, krb5 ASSESSMENT: is widely implemented in security applications. This vulnerability can lead to other exploits, dependent upon the malloc implementation and platform. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/n-062.shtml ORIGINAL BULLETIN: MIT krb5 Security Advisory 2003-005 http://web.mit.edu/kerberos/www/advisories /MITKRB5-SA-2003-005-buf.txt ADDITIONAL Information: Sun Alert ID: 54042 http://www.sunsolve.sun.com/pub-cgi/retrieve.pl?doc=fsalert %2F54042&zone_32=category%3Asecurity ______________________________________________________________________________ REVISION HISTORY: 11/12/03 - Add a link to Sun Alert ID: 54042 with patches for SEAM and Solaris. [***** Start MIT krb5 Security Advisory 2003-005 *****] -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 MIT krb5 Security Advisory 2003-005 2003-03-19 Topic: Buffer overrun and underrun in principal name handling Severity: SERIOUS SUMMARY ======= Buffer overrun and underrun problems exist in Kerberos principal name handling in unusual cases, such as names with zero components, names with one empty component, or host-based service principal names with no host name component. IMPACT ====== * Corruption of malloc pool, probably leading to program crash. + The KDC may be vulnerable. + Depending on the malloc implementation and platform, it may be possible to build more serious exploits on this. * Reference to data just past the end of an array in the KDC, for comparison against certain fixed data. May result in crashing the KDC. AFFECTED SOFTWARE ================= MIT Kerberos 5, all released versions though 1.2.7 and 1.3-alpha1. FIX === The following patches should fix the most urgent aspects of the problems in the 1.2.7 release. If these patches do not apply cleanly to 1.2.6 and earlier versions, the corresponding changes should be fairly straightforward. The patch to krb5.hin should change any missed overrun cases in this area into null pointer dereferences, which will be more likely to crash the program instead of referencing arbitrary data. Patch: http://web.mit.edu/kerberos/www/advisories/MITKRB5-SA-2003-005-patch.txt Patch PGP signature: http://web.mit.edu/kerberos/www/advisories/MITKRB5-SA-2003-005-patch.txt.asc The problem exists in other parts of the code as well, but should only result in crashing application servers when the realm has been misconfigured to use broken service names, or crashing application clients when they are supplied broken principal names. ACKNOWLEDGMENTS =============== Thanks to Nalin Dahyabhai of Red Hat for bringing the problems to our attention. CONTACT ======= For more information, contact Ken Raeburn , Sam Hartman , or Marshall Vale . This announcement and related security advisories may be found on the MIT Kerberos security advisory page at: http://web.mit.edu/kerberos/www/advisories/index.html The main MIT Kerberos web page is at: http://web.mit.edu/kerberos/www/index.html REVISION HISTORY ================ 2003-03-19 original release 2003-03-19 moved patch to separate file with separate signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: For info see http://www.gnupg.org iD8DBQE+eRggUqOaDMQ+e5gRApX+AKDn7ifSVFl0Kk5tVwNCaQRzaqIdJACgvGM2 IG2oA3cw113yv1pycbO9SkQ= =7lz1 -----END PGP SIGNATURE----- [***** End MIT krb5 Security Advisory 2003-005 *****] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Massachusetts Institute of Technology (MIT) 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: +1 925-422-8193 (7x24) FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: ciac@ciac.org Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ Anonymous FTP: ftp.ciac.org 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 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. 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) N-052: PeopleSoft PeopleTools Remote Command Execution Vulnerability N-053: Increased Activity Targeting Microsoft Windows Shares N-054: Unchecked Buffer in Windows Component Could Cause Web Server Compromise N-055: Samba smbd Buffer Overrun Vulnerability N-056: Red Hat Updated 2.4 Kernel Fix for ptrace Vulnerability N-057: Cryptographic weaknesses in Kerberos v4 protocol N-058: Vulnerabilities in Webmin/Usermin N-059: Integer overflow in Sun RPC XDR library routines N-060: Vulnerabilities in Tomcat 3.3.1 N-061: OpenSSL Timing-based Attacks on RSA Keys