-----BEGIN
PGP SIGNED MESSAGE-----
CERT Advisory
CA-2003-09 Buffer Overflow in Microsoft IIS 5.0
Original
issue date: March 17, 2003
Last revised: --
Source: CERT/CC
A complete
revision history is at the end of this file.
Systems
Affected
* Systems
running Microsoft Windows 2000 with IIS 5.0 enabled
Overview
A buffer
overflow vulnerability exists in Microsoft IIS 5.0 running on
Microsoft Windows 2000. IIS 5.0 is installed and running by default
on
Microsoft Windows 2000 systems. This vulnerability may allow a remote
attacker to run arbitrary code on the victim machine.
An exploit
is publicly available for this vulnerability, which
increases the urgency that system administrators apply a patch.
I. Description
IIS 5.0
includes support for WebDAV, which allows users to manipulate
files stored on a web server (RFC2518). A buffer overflow
vulnerability exists in ntdll.dll (a portion of code utilized by the
IIS WebDAV component). By sending a specially crafted request to an
IIS 5.0 server, an attacker may be able to execute arbitrary code in
the Local System security context, essentially giving the attacker
compete control of the system.
Microsoft
has issued the following bulletin regarding this
vulnerability:
http://www.microsoft.com/technet/treeview/default.asp?url=/technet/sec
urity/bulletin/ms03-007.asp
This vulnerability
has been assigned the identifier CAN-2003-0109 by
the Common Vulnerabilities and Exposures (CVE) group:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2003-0109
II. Impact
Any attacker
who can reach a vulnerable web server can gain complete
control of the system and execute arbitrary code in the Local System
security context. Note that this may be significantly more serious
than a simple "web defacement."
III. Solution
Apply a
patch from your vendor
A patch
is available from Microsoft at
http://microsoft.com/downloads/details.aspx?FamilyId=C9A38D45-5145-4844-B62E-C69D32AC929B&displaylang=en
Disable
vulnerable service
Until
a patch can be applied, you may wish to disable IIS. To
determine if IIS is running, Microsoft recommends the following:
Go to Start
| Settings | Control Panel | Administrative Tools | Services.
If the
World Wide Web Publishing service is listed then IIS
is installed
To disable
IIS, run the IIS lockdown tool. This tool is available
here:
http://www.microsoft.com/downloads/release.asp?ReleaseID=43955
If you
cannot disable IIS, consider using the IIS lockdown tool to
disable WebDAV (removing WebDAV can be specified when running the IIS
lockdown tool). Alternatively, you can disable WebDAV by following the
instructions located in Microsoft's Knowledgebase Article 241520, "How
to Disable WebDAV for IIS 5.0":
http://support.microsoft.com/default.aspx?scid=kb;en-us;241520
Restrict
buffer size
If you
cannot use either IIS lockdown tool or URLScan, consider
restricting the size of the buffer IIS utilizes to process requests
by
using Microsoft's URL Buffer Size Registry Tool. This tool can be run
against a local or remote Windows 2000 system running Windows 2000
Service Pack 2 or Service Pack 3. The tool, instructions on how to use
it, and instructions on how to manually make changes to the registry
are available here:
URL Buffer
Size Registry Tool - http://go.microsoft.com/fwlink/?LinkId=14875
Microsoft Knowledge Base Article 816930 - http://support.microsoft.com/default.aspx?scid=kb;en-us;816930
Microsoft
Knowledge Base Article 260694 - http://support.microsoft.com/default.aspx?scid=kb;en-us;260694
You may
also wish to use URLScan, which will block web requests that
attempt to exploit this vulnerability. Information about URLScan is
available at:
http://support.microsoft.com/default.aspx?scid=kb;[LN];326444
Appendix
A. Vendor Information
This appendix
contains information provided by vendors. When vendors
report new information, this section is updated and the changes are
noted in the revision history. If a vendor is not listed below, we
have not received their comments.
Microsoft
Corporation
Please
see Microsoft Security Bulletin MS03-007.
_________________________________________________________________
Author:
Ian A. Finlay
______________________________________________________________________
This document
is available from:
http://www.cert.org/advisories/CA-2003-09.html
______________________________________________________________________
CERT/CC
Contact Information
Email:
cert@cert.org
Phone: +1 412-268-7090 (24-hour hotline)
Fax: +1 412-268-6989
Postal address:
CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh PA 15213-3890
U.S.A.
CERT/CC
personnel answer the hotline 08:00-17:00 EST(GMT-5) /
EDT(GMT-4) Monday through Friday; they are on call for emergencies
during other hours, on U.S. holidays, and on weekends.
Using encryption
We strongly
urge you to encrypt sensitive information sent by email.
Our public PGP key is available from
http://www.cert.org/CERT_PGP.key
If you
prefer to use DES, please call the CERT hotline for more
information.
Getting
security information
CERT publications
and other security information are available from
our web site
http://www.cert.org/
To subscribe
to the CERT mailing list for advisories and bulletins,
send email to majordomo@cert.org. Please include in the body of your
message
subscribe
cert-advisory
* "CERT"
and "CERT Coordination Center" are registered in the U.S.
Patent and Trademark Office.
______________________________________________________________________
NO WARRANTY
Any material furnished by Carnegie Mellon University and the Software
Engineering Institute is furnished on an "as is" basis. Carnegie
Mellon University makes no warranties of any kind, either expressed
or
implied as to any matter including, but not limited to, warranty of
fitness for a particular purpose or merchantability, exclusivity or
results obtained from use of the material. Carnegie Mellon University
does not make any warranty of any kind with respect to freedom from
patent, trademark, or copyright infringement.
_________________________________________________________________
Conditions
for use, disclaimers, and sponsorship information
Copyright
2003 Carnegie Mellon University.
Revision
History
March
17, 2003: Initial release
-----BEGIN
PGP SIGNATURE-----
Version: PGP 6.5.8
iQCVAwUBPnYbJmjtSoHZUTs5AQHBwQQArrGYXidIN08M901XtEjXEEr7+gKuAsz5
qp8jjoG0DpQUvIa2Xmpdz2juTFTYMY0/pjX6el4BoTqGvQ2i6cJ2SWJgt1QFxXZD
TvADr9BwRqCT6+CYyAO6Q7MVEfXrJ326wBSbiibjPqw2X/hKxybMVX0LGRDyVMJO
9GIFPUipfQw=
=E602
-----END PGP SIGNATURE-----
