From secnotif@MICROSOFT.COM Fri May 7 23:15:29 1999 From: Microsoft Product Security To: MICROSOFT_SECURITY@ANNOUNCE.MICROSOFT.COM Date: Fri, 7 May 1999 19:54:56 -0700 Subject: Microsoft Security Bulletin (MS99-013) The following is a Security Bulletin from the Microsoft Product Security Notification Service. Please do not reply to this message, as it was sent from an unattended mailbox. ******************************** Microsoft Security Bulletin (MS99-013) -------------------------------------- Solution Available for File Viewers Vulnerability Originally Posted: May 7, 1999 Summary ======= Microsoft has identified a vulnerability that occurs in some file viewers that ship as part of 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. Microsoft is releasing this security bulletin to inform customers of the vulnerability and enable them to eliminate it immediately. Patches are being developed for the affected file viewers, and will be available shortly. When they are available, an update to this security bulletin will be released. 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. They are only installed under IIS if the user chooses to install the sample web files. - This vulnerability only allows a web site visitor to view files. There is no capability through this vulnerability to change files or add files to the server. - This vulnerability does not in any way bypass the Windows NT file permission ACLs. A web site visitor could only use these tools to view files whose ACLs allows them read access. The administrator of the web server determines the specific permissions for all files on the server. - 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 - The web site visitor would need to know or guess the name of each file they wished to view. Specific steps that customers can take to immediately eliminate the vulnerability are discussed below in What Customers Should Do. In addition, Microsoft is developing updated versions of the file viewers and will release them shortly. 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 provided this bulletin to inform customers of specific steps that they can take to immediately eliminate this vulnerability on their servers. Microsoft is developing updated file viewers that fix the problem identified, and will release an updated version of this bulletin when they are available. 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. (Note: It might take 24 hours from the original posting of this bulletin for the KB article to be visible in the Web-based Knowledge Base.) What Customers Should Do ======================== Customers should take the following steps to eliminate the vulnerability on their web servers: - Unless the affected file viewers are specifically required on the web site, they should be removed. The following file viewers are affected: ViewCode.asp, ShowCode.asp, CodeBrws.asp and Winmsdp.exe. Depending on the specific installation, not all of these files may be present on a server. Likewise, there may be multiple copies of some files, so customers should do a full search of their servers to locate all copies. - In accordance with standard security guidelines, file permissions should always be set to enable web visitors to access only the files they need, and no others. Moreover, files that are needed by web visitors should provide the least privilege needed; for example, files that web visitors need to be able to read but not write should be set to read-only. - As a general rule, sample files and vroots should always be deleted from a web server prior to putting it into production. If they are needed, file access permissions should be used to regulate access to them as appropriate More Information ================ Please see the following references for more information related to this issue. - Microsoft Security Bulletin MS99-013, Solution 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. 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. 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. 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