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A D V I S O R Y
97.21
******************************************************************************
Topic: Windows 95 Network Password Vulnerability
Source: CIAC
Creation Date: June 4, 1997 20:00 GMT
Last Updated:
To aid in the wide distribution of essential security information, FedCIRC is
forwarding the following information from CIAC bulletin H-68. FedCIRC urges
you to act on this information as soon as possible.
If you have any questions, please contact FedCIRC:
Telephone: +1 888 282 0870
Email: fedcirc@fedcirc.gov
=======================FORWARDED TEXT STARTS HERE============================
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************************ 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
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For emergencies and off-hour assistance, DOE, DOE contractor sites,
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Previous CIAC notices, anti-virus software, and other information are
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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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The National Institute of Standards and Technology (NIST) has
established a Federal Computer Incident response Capability (FedCIRC)
to assist federal civilians agencies in their incident handling
efforts by providing proactive and reactive computer security related
services. FedCIRC is a partnership among NIST, the Computer Incident
Advisory Capability (CIAC), and the CERT* Coordination Center
(CERT/CC).
If you believe that your system has been compromised, please contact
FedCIRC:
Telephone: +1 888 282 0870
Email: fedcirc@fedcirc.gov
Web Server: http://www.fedcirc.gov/
* Registered in U.S. Patent and Trademark Office
The CERT Coordination Center is part of the Software Engineering
Institute. The Software Engineering Institute is sponsored by the
U.S. Department of Defense.
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.
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.