Date: 23 April 1997
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AUSCERT External Security Bulletin Redistribution
ESB-97.048 -- CIAC Bulletin H-48
Internet Information Server Vulnerability
23 April 1997
CIAC has released the following advisory concerning a vulnerability
in Microsoft's Internet Information Server (IIS). This vulnerability
may allow remote users to view server-side scripts.
The following security bulletin is provided as a service to AUSCERT's
members. As AUSCERT did not write this document, AUSCERT has had
no control over its content. As such, the decision to use any or
all of this information is the responsibility of each user or
organisation, and should be done so in accordance with site policies
Contact information for CIAC is included in the Security Bulletin
below. If you have any questions or need further information,
please contact them directly.
If you believe that your system has been compromised, contact
AUSCERT or your representative in FIRST (Forum of Incident Response
and Security Teams).
Internet Email: firstname.lastname@example.org
Facsimile: (07) 3365 4477
Telephone: (07) 3365 4417 (International: +61 7 3365 4417)
AUSCERT personnel answer during Queensland business hours
which are GMT+10:00 (AEST).
On call after hours for emergencies.
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The U.S. Department of Energy
Computer Incident Advisory Capability
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Internet Information Server Vulnerability
April 18, 1997 17:00 GMT Number H-48
PROBLEM: A vulnerability in Microsoft IIS allows an outside user to view
PLATFORM: Windows NT servers running Internet Information Server 2.0 or
DAMAGE: An outside user can obtain access to sensitive Web server
SOLUTION: Apply the fix or patch provided below.
VULNERABILITY If sensitive information 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
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:
Microsoft has made information on this vulnerability available on
their Web site at:
CIAC wishes to acknowledge the contributions of Microsoft and Juan T. Llibre
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: +1 510-422-8193
FAX: +1 510-423-8002
STU-III: +1 510-423-2604
For emergencies and off-hour assistance, DOE, DOE contractor sites,
and the NIH may contact CIAC 24-hours a day. During off hours (5PM -
8AM PST), call the CIAC voice number 510-422-8193 and leave a message,
or call 800-759-7243 (800-SKY-PAGE) to send a Sky Page. CIAC has two
Sky Page PIN numbers, the primary PIN number, 8550070, is for the CIAC
duty person, and the secondary PIN number, 8550074 is for the CIAC
Previous CIAC notices, anti-virus software, and other information are
available from the CIAC Computer Security Archive.
World Wide Web: http://ciac.llnl.gov/
Anonymous FTP: ciac.llnl.gov (184.108.40.206)
Modem access: +1 (510) 423-4753 (28.8K baud)
+1 (510) 423-3331 (28.8K baud)
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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
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LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC)
H-38A: Internet Explorer 3.x Vulnerabilities
H-39: SGI IRIX fsdump Vulnerability
H-40: DIGITAL Security Vulnerabilities (DoP, delta-time)
H-41: Solaris 2.x eject Buffer Overrun Vulnerability
H-42: HP MPE/iX with ICMP Echo Request (ping) Vulnerability
H-44: Solaris 2.x fdformat Buffer Overflow Vulnerability
H-45: Windows NT SAM permission Vulnerability
H-46: Vulnerability in IMAP and POP
H-47A: AOL4FREE.COM Trojan Horse Program Destroys Hard Drives
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