Internet Information Server Vulnerability

Internet Information Server Vulnerability INFORMATION BULLETIN H-48: Internet Information Server Vulnerability April 18, 1997 21:00 GMT

PROBLEM:       A vulnerability in Microsoft IIS allows an outside user to view 
               server-side scripts. 
PLATFORM:      Windows NT servers running Internet Information Server 2.0 or 
               3.0. 
DAMAGE:        An outside user can obtain access to sensitive Web server 
               scripts. 
SOLUTION:      Apply the fix or patch provided below. 
VULNERABILITY  If sensitive informion such as passwords are present in a 
ASSESSMENT:    server-side script, this vulnerability can potentially lead to 
               compromised of a Web server. 


A vulnerability in Microsoft Internet Information Server (IIS) for
Windows NT 4.0 allows server scripts to be view by the client
side. Server-side scripts (also called script-mapped files) are
programs that produce HTML code to be viewed on the client side. It is
not intended that the scripts themselves be seen on the client side.

Commonly, server scripts contain sensitive information, such as
passwords for accessing databases. Or, seeing the content of a script
might allow an attacker to discover a way to attack the server.

To view a server script, the client user needs to simply append one or
more dots (.) to the end of the URL. For example, the URL

    http://foo.bar.org/myscript.asp.

will return the contents of the script myscript.asp, not the results
of executing the script.

All server-side scripts requested from a virtual directory that have
both read and execute permissions are vulnerable. This includes .asp,
.htx, .idc, .pl, and other types of files.

The vulnerability can be removed by disabling "read" permissions on
the virtual directory where such scripts reside. Or, the following patch
can be downloaded from Microsoft:

ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/nt40/hotfixes-postsp2/iis-fix

Microsoft has made information on this vulnerability available on
their Web site at:

http://www.microsoft.com/iis/iisnews/hotnews/security.htm

CIAC wishes to acknowledge the contributions of Microsoft and Juan T. Llibre for the information contained in this bulletin.

For additional information or assistance, please contact CIAC:

    Voice:          +1 510-422-8193 (8:00 - 18:00 PST, 16:00 - 2:00 GMT)

    Emergency (DOE, DOE Contractors, and NIH ONLY):
                     1-800-759-7243, 8550070 (primary),
                                     8550074 (secondary)
    FAX:            +1 510-423-8002
    STU-III:        +1 510-423-2604
    E-mail:          ciac@llnl.gov
    World Wide Web:  http://ciac.llnl.gov/
    Anonymous FTP:   ciac.llnl.gov (128.115.19.53)
    Modem access:   +1 (510) 423-4753 (28.8K baud)
                    +1 (510) 423-3331 (28.8K baud)

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.

UCRL-MI-119788
[Disclaimer]