Advisory CA-2002-09 Multiple Vulnerabilities in Microsoft IIS

CERT Advisory CA-2002-09 Multiple Vulnerabilities in Microsoft IIS

Original release date: April 11, 2002
Last revised: –
Source: CERT/CC

A complete revision history can be found at the end of this file.

Systems Affected

 * Microsoft IIS 4.0, 5.0, and 5.1

Overview

A variety of vulnerabilities exist in various versions of Microsoft
IIS. Some of these vulnerabilities may allow an intruder to execute
arbitrary code on vulnerable systems.

I. Description

There are a variety of vulnerabilities in Microsoft IIS. Many of these
vulnerabilities are buffer overflows that could permit an intruder to
execute arbitrary code on vulnerable systems.
We strongly encourage all sites running IIS to read Microsoft's
advisory on these and other vulnerabilities and take appropriate
action as soon as practical. Microsoft's bulletin is available at

      http://www.microsoft.com/technet/security/bulletin/MS02-018.asp

Additional information about these vulnerabilities is available at

      http://www.kb.cert.org/vuls

VU#363715 CAN-2002-0071 Microsoft Internet Information Server (IIS)
vulnerable to heap overflow during processing of crafted
".htr" request by "ISM.DLL" ISAPI filter

VU#883091 CAN-2002-0074 Microsoft Internet Information Server (IIS)
contains cross-site scripting vulnerability in IIS Help
Files search facility

VU#886699 CAN-2002-0148 Microsoft Internet Information Server (IIS)
contains cross-site scripting vulnerability in HTTP error
page results

VU#520707 CAN-2002-0075 Microsoft Internet Information Server (IIS)
contains cross-site scripting vulnerability in redirect
response messages

VU#412203 CAN-2002-0073 Microsoft Internet Information Server (IIS)
vulnerable to DoS via malformed FTP connection status
request

VU#454091 CAN-2002-0150 Microsoft Internet Information Server (IIS)
vulnerable to buffer overflow via inaccurate checking of
delimiters in HTTP header fields

VU#721963 CAN-2002-0149 Microsoft Internet Information Server (IIS)
buffer overflow in server-side includes (SSI) containing
long invalid file name

VU#521059 CAN-2002-0072 Microsoft Internet Information Server (IIS)
vulnerable to DoS when URL request exceeds maximum
allowed length

VU#610291 CAN-2002-0079 Microsoft Internet Information Server (IIS)
buffer overflow in chunked encoding transfer mechanism

VU#669779 CAN-2002-0147 Microsoft Internet Information Server (IIS)
buffer overflow in chunked encoding transfer mechanism

II. Impact

For many of the vulnerabilities, an intruder could execute arbitrary
code with privileges that vary according to which version of IIS is
running. In general, IIS 4.0 permits an intruder to execute code with
complete administrative privileges, while IIS 5.0 and 5.1 permit an
intruder to execute code with the privileges of the IWAM_computername
account.

III. Solution

Microsoft Corporation has released Microsoft Security Bulletin
MS02-018, which announces the availability of a cumulative patch to
address a variety of problems. We strongly encourage you to read this
bulletin and take the appropriate corrective measures. MS02-018 is
available at

      http://www.microsoft.com/technet/security/bulletin/MS02-018.asp

In addition to applying the patch, or until it can be applied, we
recommend the following actions:

 * Use  the  IIS Lockdown tool and URLScan to eliminate or reduce the
   impact of some of these vulnerabilites; they may also eliminate or
   reduce  other  vulnerabilities  that have not yet been discovered.
   The  IIS Lockdown tool can also be used to disable ASP if it's not
   needed.  More  information about the IIS Lockdown tool and URLScan
   can be found at

      http://www.microsoft.com/technet/security/tools/locktool.asp
            
      http://www.microsoft.com/technet/security/URLScan.asp

 * As  Microsoft has recommended for quite some time, disable the HTR
   ISAPI extension unless it is absolutely required.
 * Disable anonymous FTP unless it is required.
 * Don't give login credentials on IIS servers to untrusted users.
 _________________________________________________________________

Our thanks to Microsoft Corporation for the information contained in
their advisory. Additionally, our thanks go to the various individuals
and organizations whom Microsoft identified as discovering the
vulnerabilities, including eEye Digital Security
(http://www.eeye.com), Serge Mister of Entrust, Inc.
(http://www.entrust.com), Dave Aitel of @Stake
(http://www.atstake.com), Peter Grundl of KPMG, Joe Smith
([email protected]) and zenomorph ([email protected]) of
http://www.cgisecurity.com, Keigo Yamazaki of the LAC SNS Team
(http://www.lac.co.jp/security/), and Thor Larholm of Jubii A/S.
_________________________________________________________________

Author: Shawn V. Hernan

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This document is available from:
http://www.cert.org/advisories/CA-2002-09.html

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Revision History
April 11, 2002: Initial release