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Schwachstelle in Microsoft PPTP
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Guten Tag,
in dem angefuegten Microsoft Security Bulletin wird auf einige Sicher-
heitsprobleme bei dem Point-to-Point Tunneling Protocol (PPTP) einge-
gangen. Dieses Protocol wird von Microsoft fuer Virtual Private Networks
(VPNs) eingesetzt, hat aber einge Sicherheitsprobleme, so dass keine
sichere Verbindung mittels PPTP erstellt werden kann.
Microsoft hat entsprechende Patches zur Behebung der im Bulletin aufge-
zaehlten Schwachstellen herausgegeben. Patches fuer Windows NT beschraenken
sich dabei derzeit nur auf die US-Version von Windows NT, d.h. Benutzer
der deutschen Version haben derzeit keine Sicherungsmoeglichkeiten.
Bitte haben Sie Verstaendnis, dass auch wir Ihnen nicht sagen koennen,
wann die entsprechenden Patches fuer nicht-US-Versionen verfuegbar sein
werden.
Mit freundlichen Gruessen
Wolfgang Ley (DFN-CERT)
- --
Wolfgang Ley, DFN-CERT, Vogt-Koelln-Str. 30, 22527 Hamburg, Germany
Email: ley@xxxxxxxxxxx Phone: +49 40 5494-2262 Fax: +49 40 5494-2241
PGP-Key available via finger ley@xxxxxxxxxxxxxxx any key-server or via
WWW from http://www.cert.dfn.de/~ley/ ...have a nice day
===========================================================================
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 communcations 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/
NOTE: The above link has been wrapped for readability.
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/
NOTE: The above link has been wrapped for readability.
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
- ----------------------------------------------------------------------------
- ----
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