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__________________________________________________________
The U.S. Department of Energy
Computer Incident Advisory Center
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__________________________________________________________
INFORMATION BULLETIN
Microsoft WebDAV Runs Scripts As User
[Microsoft Bulletin MS01-022]
April 20, 2001 00:00 GMT Number L-074
______________________________________________________________________________
PROBLEM: The Microsoft WebDAV service does not differentiate between
requests made by a user and those made by a script. A user
browsing a web page containing a WebDAV script would
unknowingly run that script with the user's privilages and
possibly compromise the user's security.
PLATFORM: Microsoft Data Access Component Internet Publishing Provider.
WebDAV
DAMAGE: The owner of a malicious web page could execute scripts on the
user's behalf, giving the woner access to all of a user's web
based resources.
SOLUTION: Apply the patch as shown in Microsoft Security Bulletin
MS01-022.
http://www.microsoft.com/technet/security/bulletin/MS01-022.asp.
______________________________________________________________________________
VULNERABILITY The risk is LOW. The intruder would have to know all about the
ASSESSMENT: user's accessible resources, including file names, network
paths, etc.
______________________________________________________________________________
[***** Start Microsoft Security Bulletin *****]
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Title: WebDAV Service Provider Can Allow Scripts to Levy
Requests as User
Date: 18 April 2001
Software: Microsoft Data Access Component Internet Publishing
Provider
Impact: Web-based script could levy WebDAV requests on the user's
behalf.
Bulletin: MS01-022
Microsoft encourages customers to review the Security Bulletin at:
http://www.microsoft.com/technet/security/bulletin/MS01-022.asp.
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Issue:
======
The Microsoft Data Access Component Internet Publishing Provider
provides access to WebDAV resources over the Internet. By design, it
should differentiate between requests made by a user and those made by
a script running in the user's browser. However, because of an
implementation flaw, it handles all requests in the security context of
the user. As a result, if a user browsed to a web page or opened an
HTML e-mail that contained script, that script could access web-based
resources as the user.
The specific actions an attacker could take via this vulnerability
would depend on the Web-based resources available to the user, and the
user's privileges on them. However, it is likely that at a minimum, the
attacker could browse the user's intranet, and potentially access
web-based e-mail as well.
Mitigating Factors:
====================
- The attacker would need to possess significant inside information in
order to carry out a successful attack, such as server names, folder
structures, and other user- and network-specific information. This
vulnerability would therefore be most likely used as part of an
insider attack.
- The vulnerability could not be exploited against stand-alone
machines.
- The vulnerability could not be exploited if Active Scripting was
disabled in the Security Zone the script opened in.
Patch Availability:
===================
- A patch is available to fix this vulnerability. Please read the
Security Bulletin
http://www.microsoft.com/technet/security/bulletin/ms01-022.asp
for information on obtaining this patch.
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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 Security Bulletin *****]
______________________________________________________________________________
CIAC wishes to acknowledge the contributions of 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: +1 925-422-8193 (7x24)
FAX: +1 925-423-8002
STU-III: +1 925-423-2604
E-mail: ciac@ciac.org
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)
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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