-----BEGIN PGP SIGNED MESSAGE----- ************************ FOR PUBLIC RELEASE ***************************** __________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Windows 95 Network Password Vulnerability June 4, 1997 20:00 GMT Number H-68 ______________________________________________________________________________ PROBLEM: A vulnerability has been identified in the way Windows 95 network passwords are stored in memory on the local machine. PLATFORM: All systems running Microsoft Windows 95. DAMAGE: This vulnerability can lead to unauthorized access to a user's network account. SOLUTION: Apply the necessary patches indicated below. ______________________________________________________________________________ VULNERABILITY Information about this vulnerability is widely distributed. ASSESSMENT: ______________________________________________________________________________ [ Start AUSCERT Advisory ] =========================================================================== AA-97.25 AUSCERT Advisory Windows95 Network Password Vulnerability 3 June 1997 Last Revised: -- - ---------------------------------------------------------------------------- AUSCERT has received information that a vulnerability exists in the way that network passwords are stored in memory by Microsoft Windows95 systems. This vulnerability may allow the unauthorised access to the plain text password for the currently logged in user. This can lead to unauthorised access to the user's network account. Microsoft has released a security bulletin, containing patch information, addressing the vulnerability. These patches encrypt the passwords stored in memory. The security bulletin and patches are described in this advisory. - ---------------------------------------------------------------------------- 1. Description A vulnerability exists in the way that network passwords are stored in memory by Microsoft Windows95 systems. This vulnerability may allow unauthorised access to the plain text password for the currently logged in user. Although the password is encrypted before sending it over a network, it is stored unencrypted in the system's memory. Access to the password for the currently logged in user is possible through careful examination of memory structures. It is possible to develop a program to simplify this attack. To obtain the password currently stored in memory, a program must be executed on the system. This can be done by either gaining physical access to the computer or misleading the user into executing the program. These actions must be performed while the network user is still logged in. The user can be misled into running a malicious program by downloading untrusted information from the Internet, or by some other means such as embedding the malicious program in a Macro contained in a file that gets executed when the file is opened by the user. This file may be sent to the user as an attachment to an electronic mail message. 2. Impact Unauthorised access may be gained to the network password of the user logged in to a Windows95 system. This can lead to unauthorised access to the user's network account using the compromised password. 3. Workarounds/Solution Official vendor patches have been released by Microsoft which address this vulnerability (Section 3.1). AUSCERT recommends that sites apply the patches given in this bulletin immediately. 3.1 Install vendor patches Microsoft has released a security bulletin, containing patch information, addressing the vulnerability described in this advisory. This bulletin can be located on their security page on Microsoft's Web site at http://www.microsoft.com/security/ and is titled "Microsoft Windows 95 Update to Enhance Password Security". Additionally, a Microsoft Knowledge Base article has been developed by Microsoft detailing more information about this problem and associated fixes. It can be located by going to Microsoft Australia's home page (http://www.microsoft.com.au) and following the links to "Support", and then to "Knowledge Base". The specific Knowledge Base article to search for is Q165402. This article can also be referenced as http://www.microsoft.com/kb/articles/q165/4/02.htm Both the bulletin and the Knowledge Base article contain pointers to patches that can be downloaded. AUSCERT recommends that sites apply the patches given in this bulletin immediately. 4. Additional Measures To gain access to the user's password, the user must first be logged in to the network from a Windows95 system using their account and password. The password is obtained by either someone running a program on the system, or a program must be executed by the user or on the user's behalf. Executing a program can be done by either gaining physical access to the system or misleading the user into running an untrusted program. The user can be misled into running a malicious program by downloading untrusted information from the Internet, or by some other means such as embedding the malicious program in a Macro contained in a file that gets executed when the file is opened by the user. This file may be sent to the user as an attachment to an electronic mail message. Educating users can address each of these scenarios. The ability to exploit this vulnerability can be reduced if unauthorised access to the system, while the user is still logged in, can be minimised or eliminated. One way this can be achieved is if each user logs off from the network any time they leave the computer for reasonable periods of time, or runs a password protected screen saver. Users should also be educated not to run untrusted programs that have been given to them on disk or via Email, or downloaded from a network. Email attachments should be scanned for any unauthorised macros. - - --------------------------------------------------------------------------- AUSCERT thanks the Australian Bureau of Statistics and Microsoft for their assistance and response in the preparation of this Advisory. n --------------------------------------------------------------------------- n [ End AUSCERT Advisories ] ______________________________________________________________________________ CIAC wishes to acknowledge the contributions of AUSCERT, the Australian Bureau of Statistics, and Microsoft 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 (198.128.39.53) 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 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, ciac-notes, 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-notes 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. 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