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AUSCERT External Security Bulletin Redistribution
ESB-2001.241 -- CERT Advisory CA-2001-13
Buffer Overflow In IIS Indexing Service DLL
20 June 2001
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AusCERT Security Bulletin Summary
---------------------------------
Product: Microsoft Index Server 2.0
Indexing Service in Windows 2000
Indexing Service in Windows XP beta
Vendor: Microsoft
Operating System: Microsoft Windows NT 4.0 with IIS 4.0 or IIS 5.0
Microsoft Windows 2000 Professional
Microsoft Windows 2000 Server
Microsoft Windows 2000 Advanced Server
Microsoft Windows 2000 Datacenter Server
Microsoft Windows XP beta
Impact: Execute Arbitrary Code/Commands
Administrator Compromise
Access Required: Remote
Ref: ESB-2001.238
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CERT Advisory CA-2001-13 Buffer Overflow In IIS Indexing Service DLL
Original release date: June 19, 2001
Last revised: --
Source: CERT/CC
A complete revision history is at the end of this file.
Systems Affected
* Systems running Microsoft Windows NT 4.0 with IIS 4.0 or IIS 5.0
enabled
* Systems running Microsoft Windows 2000 (Professional, Server,
Advanced Server, Datacenter Server)
* Systems running beta versions of Microsoft Windows XP
Overview
A vulnerability exists in the Indexing Services used by Microsoft IIS
4.0 and IIS 5.0 running on Windows NT, Windows 2000, and beta versions
of Windows XP. This vulnerability allows a remote intruder to run
arbitrary code on the victim machine.
Since specific technical details on how to create an exploit are
publicly available for this vulnerability, system administrators
should apply fixes or workarounds on affected systems as soon as
possible.
I. Description
There is a remotely exploitable buffer overflow in one of the ISAPI
extensions installed with most versions of IIS 4.0 and 5.0 (The
specific Internet/Indexing Service Application Programming Interface
extension is IDQ.DLL). An intruder exploiting this vulnerability may
be able to execute arbitrary code in the Local System security
context. This essentially can give the attacker complete control of
the victim system.
This vulnerability was discovered by eEye Digital Security. Microsoft
has released the following bulletin regarding this issue:
http://www.microsoft.com/technet/security/bulletin/MS01-033.asp
Affected versions of Windows include Windows NT 4.0 (installed with
IIS 4.0 and Index Server 2.0), Windows 2000 (Server and Professional
with IIS 5.0 installed), and Windows 2000 Datacenter Server OEM
distributions; however, not all of these instances are vulnerable by
default. The beta versions of Windows XP are vulnerable by default.
The only precondition for exploiting this vulnerability is that an IIS
server is running with script mappings for Internet Data
Administration (.ida) and Internet Data Query (.idq) files. The
Indexing Services do not need to be running. As stated by Microsoft in
MS01-033:
The buffer overrun occurs before any indexing functionality is
requested. As a result, even though idq.dll is a component of
Index Server/Indexing Service, the service would not need to be
running in order for an attacker to exploit the vulnerability.
As long as the script mapping for .idq or .ida files were
present, and the attacker were able to establish a web session,
he could exploit the vulnerability.
This vulnerability has been assigned the identifier CAN-2001-0500 by
the Common Vulnerabilities and Exposures (CVE) group:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2001-0500
II. Impact
Anyone who can reach a vulnerable web server can execute arbitrary
code in the Local System security context. This results in the
intruder gaining complete control of the system. Note that this may be
significantly more serious than a simple "web defacement."
III. Solution
Apply a patch from your vendor
Apply patches for vulnerable Windows NT 4.0 and Windows 2000 systems:
For Windows NT 4.0:
http://www.microsoft.com/Downloads/Release.asp?ReleaseID=30833
For Windows 2000 Professional, Server, and Advanced Server:
http://www.microsoft.com/Downloads/Release.asp?ReleaseID=30800
These patches supersede the ones previously provided in Microsoft
Security Bulletins MS01-025 and MS00-006.
Users of Windows 2000 Datacenter Server software should contact their
original equipment manufacturer (OEM) for patches. A list of OEM
providers may be found here:
http://www.microsoft.com/windows2000/datacenter/howtobuy/purchasing/oems.asp
Workarounds
Users of beta copies of Windows XP should upgrade to a newer version
of the software when it becomes available.
All affected versions of IIS/Indexing Services can be protected
against exploits of this vulnerability by removing script mappings for
for Internet Data Administration (.ida) and Internet Data Query (.idq)
files. However, such mappings may be recreated when installing other
related software components.
Appendix A. Vendor Information
Microsoft Corporation
The following documents regarding this vulnerability are available
from Microsoft:
http://www.microsoft.com/technet/security/bulletin/MS01-033.asp
References
1. VU#952336: Microsoft Index Server/Indexing Service used by IIS
4.0/5.0 contains unchecked buffer used when encoding double-byte
characters CERT/CC, 06/19/2001,
https://www.kb.cert.org/vuls/id/952336
2. Additional advice on securing IIS web servers is available from
http://www.microsoft.com/technet/security/iis5chk.asp
http://www.microsoft.com/technet/security/tools.asp
Feedback concerning this document may be directed to Jeffrey S.
Havrilla.
______________________________________________________________________
This document is available from:
http://www.cert.org/advisories/CA-2001-13.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.
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______________________________________________________________________
NO WARRANTY
Any material furnished by Carnegie Mellon University and the Software
Engineering Institute is furnished on an "as is" basis. Carnegie
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_________________________________________________________________
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Copyright 2001 Carnegie Mellon University.
Revision History
Jun 19, 2001: Initial Release
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