The following is a Security Bulletin from the Microsoft Product Security
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Update to Microsoft Security Bulletin (MS99-013)
------------------------------------------------
Patches Available for File Viewers Vulnerability
Originally Posted: May 7, 1999
Updated: May 19, 1999
Summary
=======
This is an update to Microsoft Security Bulletin MS99-013. The purpose of
the update is to advise customers of the availability of patches that
eliminate a vulnerability that occurs in some file viewers included in
Microsoft (r) Internet Information Server and Site Server. The vulnerability
could allow a web site visitor to view, but not to change, files on the
server, provided that they knew or guessed the name of each file and had
access rights to it based on Windows NT ACLs.
Issue
=====
Microsoft Site Server and Internet Information Server include tools that
allow web site visitors to view selected files on the server. These are
installed by default under Site Server, but must be explicitly installed
under IIS. These tools are provided to allow users to view the source code
of sample files as a learning exercise, and are not intended to be deployed
on production web servers. The underlying problem in this vulnerability is
that the tools do not restrict which files a web site visitor can view.
It is important to note several important points:
- These file viewers are not installed by default under IIS.
- The web site visitor would need to know or guess the name
of each file they wished to view.
- This vulnerability only allows a web site visitor to view
files, not to change them or to create new ones.
- The file viewers are subject to normal Windows NT file
permission ACLs. A web site visitor could only use the file
viewers to read files for which they have read access.
- The viewers can only be used to view files on the same disk
partition as the currently-displayed web page. Databases such
as those used by e-commerce servers are typically stored on a
different physical drive, and these would not be at risk.
While there are no reports of customers being adversely affected by this
vulnerability, Microsoft is proactively releasing this bulletin to allow
customers to take appropriate action to protect themselves against it.
Affected Software Versions
==========================
- Microsoft Site Server 3.0, which is included with Microsoft
Site Server 3.0 Commerce Edition, Microsoft Commercial
Internet System 2.0, and Microsoft BackOffice Server 4.0 and 4.5
- Microsoft Internet Information Server 4.0
What Microsoft is Doing
=======================
Microsoft has released patches that fix the problem identified. The patches
are available for download from the sites listed below in What Customers
Should Do.
Microsoft also has sent this security bulletin to customers subscribing
to the Microsoft Product Security Notification Service. See
http://www.microsoft.com/security/services/bulletin.asp for more
information about this free customer service.
Microsoft has published the following Knowledge Base (KB) article on this
issue:
- Microsoft Knowledge Base (KB) article Q231368,
Solution Available for File Viewers Vulnerability,
http://support.microsoft.com/support/kb/articles/q231/3/68.asp.
- Microsoft Knowledge Base (KB) article Q231656,
Preventing Viewcode.asp from Viewing Known Server Files,
http://support.microsoft.com/support/kb/articles/q231/6/56.asp.
(Note: It might take 24 hours from the posting of the bulletin for the
updates to the KB articles to be visible in the Web-based Knowledge Base.)
What Customers Should Do
========================
Microsoft highly recommends that customers evaluate the degree of risk that
this vulnerability poses to their systems and determine whether to download
and install the patch. The patch can be found at:
- Internet Information Server:
ftp://ftp.microsoft.com/bussys/iis/iis-public/fixes/usa/Viewcode-fix/
- Site Server:
ftp://ftp.microsoft.com/bussys/sitesrv/sitesrv-public/fixes
/usa/siteserver3/hotfixes-postsp2/Viewcode-fix/
NOTE: The above URLs have been word-wrapped for readability.
Microsoft has provided a checklist that customers can use to ensure that
their web servers have been properly secured. This checklist is available
at http://www.microsoft.com/security/products/iis/checklist.asp
More Information
================
Please see the following references for more information related to this
issue.
- Microsoft Security Bulletin MS99-013,
Patches Available for File Viewers Vulnerability
(The Web-posted version of this bulletin),
http://www.microsoft.com/security/bulletins/ms99-013.asp.
- Microsoft Knowledge Base (KB) article Q231368,
Solution Available for File Viewers Vulnerability,
http://support.microsoft.com/support/kb/articles/q231/3/68.asp.
- Microsoft Knowledge Base (KB) article Q231656,
Preventing Viewcode.asp from Viewing Known Server Files,
http://support.microsoft.com/support/kb/articles/q231/6/56.asp.
Obtaining Support on this Issue
===============================
If you require technical assistance with this issue, please
contact Microsoft Technical Support. For information on contacting
Microsoft Technical Support, please see
http://support.microsoft.com/support/contact/default.asp.
Acknowledgments
===============
Microsoft acknowledges WebTrends (www.webtrends.com) for discovering this
vulnerability and reporting it to us.
Revisions
=========
- May 07, 1999: Bulletin Created.
- May 19, 1999: Bulletin updated to provide patch information.
For additional security-related information about Microsoft products, please
visit http://www.microsoft.com/security
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