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TUCoPS :: Windows Net Apps :: ciaci087.txt

Microsoft Pptp Security Vulnerabilities




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             __________________________________________________________

                       The U.S. Department of Energy
                    Computer Incident Advisory Capability
                           ___  __ __    _     ___
                          /       |     /_\   /
                          \___  __|__  /   \  \___
             __________________________________________________________

                             INFORMATION BULLETIN

                    Microsoft PPTP Security Vulnerabilities

August 19, 1998 16:00 GMT                                         Number I-087
______________________________________________________________________________
PROBLEM:       Microsoft has identified vulnerabilities in the Point-to-Point
               Tunneling Protocol (PPTP).
PLATFORM:      Microsoft Dialup Networking 1.2x and earlier on Windows 95.
               Microsoft Remote Access Services on Windows NT 4.0.
               Microsoft Routing and Remote Access Services on Windows NT
                 Server 4.0.
               Microsoft Windows 98 Dialup Networking.
DAMAGE:        Dictionary attack against the LAN Manager authentication
                 information.
               Password theft.
               PPTP server spoofing.
               Reuse of MPPE session keys.
SOLUTION:      Apply available patches.
______________________________________________________________________________
VULNERABILITY  Risk is high. Exploitation of these vulnerabilities could allow
ASSESSMENT:    the capture of passwords or viewing the contents of encrypted
               sessions.
______________________________________________________________________________

[  Start Microsoft Corp. Advisory  ]


Microsoft Security Bulletin (MS98-012)


- ------------------------------------------------------------------------------


Updates available for Security Vulnerabilities in Microsoft PPTP

Originally Posted: August 18, 1998
Last Revised: August 18, 1998

Summary

Microsoft has released a set of patches that fix several security issues with
implementations of the Point-to-Point Tunneling Protocol (PPTP) used in
Microsoft Virtual Private Networking (VPN) products. Customers using affected
software listed below to secure communications over a public network (i.e. the
Internet) should download and apply these patches as soon as possible.

Customers who are not using PPTP for network security are not affected by this
issue.


Issue

The Microsoft implementation of PPTP uses MS-CHAP for user authentication and
Microsoft Point-to-Point Encryption (MPPE) to protect the confidentiality of
user data. Potential vulnerabilities addressed by these updates include:

  Dictionary attack against the LAN Manager authentication information
  Password theft
  PPTP server spoofing
  Reuse of MPPE session keys

While there have not been any reports of customers being adversely affected by
these problems, Microsoft is releasing these patches to address the implied
risks posed by these issues.


Affected Software Versions

The following software is affected by this vulnerability:

Microsoft Dialup Networking 1.2x and earlier on Windows 95
Microsoft Remote Access Services on Windows NT 4.0 (both client and server)
Microsoft Routing and Remote Access Services on Windows NT Server 4.0
Microsoft Windows 98 Dialup Networking


What Microsoft is Doing

On August 18th Microsoft released a set of patches that fix the problems
identified. These patches are available for download by Windows NT, Windows 95
and Windows 98 customers from the Microsoft FTP site.

Microsoft has sent this security bulletin to customers subscribing to the
Microsoft Product Security Notification Service (see
http://www.microsoft.com/security/bulletin.htm for more information about this
free customer service).

Microsoft has published the following Knowledge Base (KB) articles on this
issue:

Microsoft Knowledge Base (KB) article Q154091, Windows 95 Dial-Up Networking
1.3 Upgrade Release Notes
http://support.microsoft.com/support/kb/articles/q154/0/91.asp
Microsoft Knowledge Base (KB) article Q189594, RRAS Hotfix 3.0
http://support.microsoft.com/support/kb/articles/q189/5/94.asp
Microsoft Knowledge Base (KB) article Q189595, Windows NT 4.0 PPTP Security
Update http://support.microsoft.com/support/kb/articles/q189/5/95.asp
Microsoft Knowledge Base (KB) article Q189771, Windows 98 PPTP Security Update
http://support.microsoft.com/support/kb/articles/q189/7/71.asp


What customers should do

Microsoft highly recommends that users of affected software versions, listed
in the "Affected Software Versions" section above, should download the
appropriate patch. Complete URLs for each affected software version is given
below.

Windows NT 4.0 RAS Users
Download the patch from:
ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/NT40/hotfixes-
postSP3/pptp3-fix/

Windows NT 4.0 RRAS Users
Download the patch from:
ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/NT40/hotfixes-
postSP3/rras30-fix/

Windows 95 Users
Download the patch from:
ftp://ftp.microsoft.com/softlib/mslfiles/msdun13.exe

Windows 98 Users
Download the patch from:
ftp://ftp.microsoft.com/softlib/mslfiles/dun40.exe

Strong Encryption Versions (128-bit)
Customers in the United States and Canada can download the strong encryption
versions of these updates from:
http://mssecure.www.conxion.com/cgi-bin/ntitar.pl


More Information

Please see the following references for more information related to this
issue.

Microsoft Security Bulletin MS98-012, Updates available for Security
Vulnerabilities in Microsoft PPTP, (the Web posted version of this bulletin),
http://www.microsoft.com/security/bulletins/ms98-012.htm
Microsoft Knowledge Base (KB) article Q154091, Windows 95 Dial-Up Networking
1.3 Upgrade Release Notes
http://support.microsoft.com/support/kb/articles/q154/0/91.asp
Microsoft Knowledge Base (KB) article Q189594, RRAS Hotfix 3.0
http://support.microsoft.com/support/kb/articles/q189/5/94.asp
Microsoft Knowledge Base (KB) article Q189595, Windows NT 4.0 PPTP Security
Update http://support.microsoft.com/support/kb/articles/q189/5/95.asp
Microsoft Knowledge Base (KB) article Q189771, Windows 98 PPTP Security Update
http://support.microsoft.com/support/kb/articles/q189/7/71.asp


Revisions

August 18, 1998: Bulletin Created
For additional security-related information about Microsoft products, please
visit http://www.microsoft.com/security



- ------------------------------------------------------------------------------


THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS"
WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER
EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS
SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT,
INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN
IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY
OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF
LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION
MAY NOT APPLY.


[  End Microsoft Corp. Advisory  ]

______________________________________________________________________________

CIAC wishes to acknowledge the contributions of Microsoft Corp. 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.

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