-----BEGIN PGP SIGNED MESSAGE----- __________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Microsoft Exchange Denial of Service Attacks August 5, 1998 22:00 GMT Number I-080 ______________________________________________________________________________ PROBLEM: Vulnerabilites have been identified in the Exchange Internet Mail Service (IMS), the service that handles the SMTP protocol, and the Information Store, the service that handles the NNTP protocol PLATFORM: Microsoft Exchange Server 5.0 and 5.5. DAMAGE: If exploited, an attacker may be able to cause a Denial of Service. SOLUTION: Apply hotfixes. If you cannot apply the hotfix immediately, Microsoft recommends that you configure the Server Monitor in Microsoft Exchange Server Administrator to automatically restart the affected services if they stop. ______________________________________________________________________________ VULNERABILITY An attacker can disrupt an organization by crashing a Microsoft ASSESSMENT: Exchange Server over the network. This attack will stop e-mail and other services that Exchange provides for the organization. ______________________________________________________________________________ [ Start ISS Security Advisory ] ====================== ISS Security Advisory July 24, 1998 Denial of Service attacks against Microsoft Exchange 5.0 to 5.5 Synopsis: An attacker can disrupt an organization by crashing Microsoft Exchange Server over the network. This attack will stop e-mail and other services that Exchange provides for the organization. Recommended Action: Install vendor supplied hotfixes for Microsoft Exchange 5.0, and 5.5. Hotfixes are available for Exchange 5.0 and 5.5 at the following locations: Exchange Server 5.0 ALL LANGUAGES: ftp://ftp.microsoft.com/bussys/exchange/exchange-public/fixes/ Eng/Exchg5.0/Post-SP2-STORE/ ftp://ftp.microsoft.com/bussys/exchange/exchange-public/fixes/ Eng/Exchg5.0/Post-SP2-IMS/ Exchange Server 5.5 ENGLISH: ftp://ftp.microsoft.com/bussys/exchange/exchange-public/fixes/ Eng/Exchg5.5/PostRTM/STORE-FIX ftp://ftp.microsoft.com/bussys/exchange/exchange-public/fixes/ Eng/Exchg5.5/PostRTM/IMS-FIX Exchange Server 5.5 FRENCH: ftp://ftp.microsoft.com/bussys/exchange/exchange-public/fixes/ Frn/Exchg5.5/PostRTM/STORE-FIX ftp://ftp.microsoft.com/bussys/exchange/exchange-public/fixes/ Frn/Exchg5.5/PostRTM/IMS-FIX Exchange Server 5.5 GERMAN: ftp://ftp.microsoft.com/bussys/exchange/exchange-public/fixes/ Ger/Exchg5.5/PostRTM/STORE-FIX ftp://ftp.microsoft.com/bussys/exchange/exchange-public/fixes/ Ger/Exchg5.5/PostRTM/IMS-FIX Exchange Server 5.5 JAPANESE: ftp://ftp.microsoft.com/bussys/exchange/exchange-public/fixes/ Jpn/Exchg5.5/PostRTM/STORE-FIX ftp://ftp.microsoft.com/bussys/exchange/exchange-public/fixes/ Jpn/Exchg5.5/PostRTM/IMS-FIX If you cannot apply the hotfix immediately, Microsoft recommends that you configure the Server Monitor in Microsoft Exchange Server Administrator to automatically restart the affected services if they stop. Determining if you are vulnerable: If you are running Microsoft Exchange 5.0 or 5.5 without appropriate hotfixes, you are vulnerable to the attacks. Description: There are vulnerabilities in the Exchange Internet Mail Service (IMS), the service that handles the SMTP protocol, and the Information Store, the service that handles the NNTP protocol, that will allow an attacker to crash the Internet Mail Service or the Information Store. These vulnerabilities are related to the way that the IMS handles the AUTH command and how the Information Store's NNTP server handles AUTHINFO. Both of these systems experience buffer overflow issues. A similar problem not related to the buffer overflow issue involves how IMS handles the AUTH command. This issue will also cause the service to crash. Note that when the Internet Mail Service crashes, the rest of Microsoft Exchange will still operate. When the Information Store crashes, Exchange Server cannot operate. Vulnerable Versions: Microsoft Exchange Server 5.0 and 5.5 are vulnerable without hotfixes applied Additional Information: There are two Microsoft Knowledge Base articles that address these issues - -- Q188369 and Q188341. These can be obtained from Microsoft Support Online at http://support.microsoft.com. ISS X-Force thanks the Microsoft Exchange group for providing assistance and patches to these issues in a timely fashion. These security issues were discovered by Jon Larimer of ISS X-Force . - -------- Copyright (c) 1998 by Internet Security Systems, Inc. Permission is hereby granted for the redistribution of this Alert electronically. It is not to be edited in any way without express consent of X-Force. If you wish to reprint the whole or any part of this Alert in any other medium excluding electronic medium, please e-mail xforce@iss.net for permission. Disclaimer The information within this paper may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties with regard to this information. In no event shall the author be liable for any damages whatsoever arising out of or in connection with the use or spread of this information. Any use of this information is at the user's own risk. X-Force PGP Key available at: http://www.iss.net/xforce/sensitive.html as well as on MIT's PGP key server and PGP.com's key server. X-Force Vulnerability and Threat Database: http://www.iss.net/xforce Please send suggestions, updates, and comments to: X-Force of Internet Security Systems, Inc. - -------------- [ End ISS Security Advisory ] ______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Internet Security Systems, 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. 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 FAX: +1 925-423-8002 STU-III: +1 925-423-2604 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 925-422-8193 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://www.ciac.org/ (or http://ciac.llnl.gov -- they're the same machine) Anonymous FTP: ftp.ciac.org (or ciac.llnl.gov -- they're the same machine) Modem access: +1 (925) 423-4753 (28.8K baud) +1 (925) 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. SPI-ANNOUNCE for official news about Security Profile Inspector (SPI) software updates, new features, distribution and availability; 3. 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 Majordomo, 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, spi-announce OR spi-notes for list-name: E-mail to ciac-listproc@llnl.gov or majordomo@tholia.llnl.gov: subscribe list-name e.g., subscribe ciac-bulletin You will receive an acknowledgment email immediately with a confirmation that you will need to mail back to the addresses above, as per the instructions in the email. This is a partial protection to make sure you are really the one who asked to be signed up for the list in question. If you include the word 'help' in the body of an email to the above address, it will also send back an information file on how to subscribe/unsubscribe, get past issues of CIAC bulletins via email, etc. 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) I-070: Distributed DoS Attack Against NIS/NIS+ Networks I-071: OpenVMS loginout Vulnerability I-072: SunOS Solaris Vulnerabilities (libnsl, SUNWadmap) I-073: multiscan ('mscan') Tool I-074: Buffer Overflow in Some Implementations of IMAP Servers I-075: Microsoft Office 98 Security Vulnerability I-076: SGI IRIX ioconfig(1M) and disk_bandwidth(1M) Vulnerability I-077: Mime Name Vulnerability in Outlook and Messenger I-078: HP-UX ftp Security Vulnerability I-079: IBM AIX "sdrd" daemon Vulnerability -----BEGIN PGP SIGNATURE----- Version: 4.0 Business Edition iQCVAwUBNcorYbnzJzdsy3QZAQGkawQA2KrktAl1d/+RJudLOg3ffxHD4qMk1UuQ JY7eLrPVqV8X0TF3cjulxTIZmQjlssjMhAqjUpUZFg5YmdCGyg2RH+U7KTLpR995 ovHVf27d19ELdvdy4KikXgaZuhCi6hJYiBZ/IbTW8ioiaVam9S+jQKgFfz1IP84K kQRO3FsJMRg= =I9pM -----END PGP SIGNATURE-----