Published:
18 June 2001
Protect yourself against future threats.
-----BEGIN PGP SIGNED MESSAGE-----
===========================================================================
AUSCERT External Security Bulletin Redistribution
ESB-2001.238 -- Microsoft Security Bulletin MS01-033
Unchecked Buffer in Index Server ISAPI Extension Could Enable Web Server Compromise
19 June 2001
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: Microsoft Index Server 2.0
Indexing Service in Windows 2000
Indexing Service in Windows XP beta
Vendor: Microsoft
Impact: Execute Arbitrary Code/Commands
Access Required: Remote
- --------------------------BEGIN INCLUDED TEXT--------------------
- -----BEGIN PGP SIGNED MESSAGE-----
- - ----------------------------------------------------------------------
Title: Unchecked Buffer in Index Server ISAPI Extension Could
Enable Web Server Compromise
Date: 18 June 2001
Software: Index Server 2.0 and Indexing Service
Impact: Run code of attacker's choice
Bulletin: MS01-033
Microsoft encourages customers to review the Security Bulletin at:
http://www.microsoft.com/technet/security/bulletin/MS01-033.asp.
- - ----------------------------------------------------------------------
Issue:
======
As part of its installation process, IIS installs several ISAPI
extensions -- .dlls that provide extended functionality. Among these
is
idq.dll, which is a component of Index Server (known in Windows 2000
as
Indexing Service) and provides support for administrative scripts
(.ida
files) and Internet Data Queries (.idq files).
A security vulnerability results because idq.dll contains an
unchecked
buffer in a section of code that handles input URLs. An attacker who
could establish a web session with a server on which idq.dll is
installed could conduct a buffer overrun attack and execute code on
the
web server. Idq.dll runs in the System context, so exploiting the
vulnerability would give the attacker complete control of the server
and allow him to take any desired action on it.
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.
Clearly, this is a serious vulnerability, and Microsoft urges all
customers to take action immediately. Customers who cannot install
the
patch can protect their systems by removing the script mappings for
.idq and .ida files via the Internet Services Manager in IIS.
However,
as discussed in detail in the FAQ, it is possible for these mappings
to
be automatically reinstated if additional system components are added
or removed. Because of this, Microsoft recommends that all customers
using IIS install the patch, even if the script mappings have been
removed.
Mitigating Factors:
====================
- The vulnerability can only be exploited if a web session
can be established with an affected server. Customers
who have installed Index Server or Index Services but not
IIS would not be at risk. This is the default case for
Windows 2000 Professional.
- The vulnerability cannot be exploited if the script mappings
for Internet Data Administration (.ida) and Internet Data
Query (.idq) files are not present. The procedure for
removing the mappings is discussed in the IIS 4.0
(http://www.microsoft.com/technet/security/iischk.asp) and IIS
5.0 (http://www.microsoft.com/technet/security/iis5chk.asp)
Security checklists, can be automatically removed via either
the High Security Template or the Windows 2000 Internet Server
Security Tool
(http://www.microsoft.com/technet/security/tools.asp).
Customers should be aware, however, that subsequently adding
or removing system components can cause the mapping to be
reinstated, as discussed in the FAQ.
- An attacker's ability to extend control from a compromised web
server to other machines would depend heavily on the specific
configuration of the network. Best practices recommend that the
network architecture account for the inherent high-risk that
machines in an uncontrolled environment, like the Internet,
face by minimizing overall exposure though measures like DMZ's,
operating with minimal services and isolating contact with
internal networks. Steps like this can limit overall exposure
and impede an attacker's ability to broaden the scope of a
possible compromise.
Patch Availability:
===================
- A patch is available to fix this vulnerability. Please read the
Security Bulletin
http://www.microsoft.com/technet/security/bulletin/ms01-033.asp
for information on obtaining this patch.
Acknowledgment:
===============
- eEye Digital Security (http://www.eeye.com)
- - ---------------------------------------------------------------------
THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED
"AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL
WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
SHALL
MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES
WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL,
LOSS
OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION
OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH
DAMAGES.
SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR
CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY
NOT
APPLY.
- -----BEGIN PGP SIGNATURE-----
Version: PGP Personal Privacy 6.5.3
iQEVAwUBOy5cV40ZSRQxA/UrAQFixQf/T7TzDv7UnbRJGNJhTlotVp73M8Gz0Plf
1m/Axqx4/qo6oA1hwM4RRrCU6eJ30HEmwORAwKabZoewK8Vpqc5FLquHoJLFsiFo
5K1wD7/FmUnwEHu8UGpooNKelYxehnbOatms87jE4Oq9GCDnDGlQN9V+oIYccqBA
05RmF7Vm0Z9e8qOonrl58LiwjIItDnkAutOHTO6OEDwRf71VfL4xCfU8Vz2t1zc/
tRPVEgEk4WqHOkYw5ZOsmI0/khnzF14M6sbpKf8pj+vOKKb/qNRrhU2MvBOu4b/U
4JQEuFNQbqTyZvcD9p5cm8IVfjxv6Tx/blpr4tLk/3ZnL8IyWX/QxQ==
=i6pf
- -----END PGP SIGNATURE-----
- --------------------------END INCLUDED TEXT--------------------
You have received this e-mail bulletin as a result of your organisation's
registration with AusCERT. The mailing list you are subscribed to is
maintained within your organisation, so if you do not wish to continue
receiving these bulletins you should contact your local IT manager. If
you do not know who that is, please send an email to auscert@auscert.org.au
and we will forward your request to the appropriate person.
This security bulletin is provided as a service to AusCERT's members. As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. 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 and procedures.
NOTE: This is only the original release of the security bulletin. It may
not be updated when updates to the original are made. If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the original authors to ensure that the information is still current.
Contact information for the authors of the original document is included
in the Security Bulletin above. If you have any questions or need further
information, please contact them directly.
Previous advisories and external security bulletins can be retrieved from:
http://www.auscert.org.au/Information/advisories.html
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: auscert@auscert.org.au
Facsimile: (07) 3365 7031
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.
-----BEGIN PGP SIGNATURE-----
Version: 2.6.3i
Charset: noconv
Comment: ftp://ftp.auscert.org.au/pub/auscert/AUSCERT_PGP.key
iQCVAwUBOy8aUSh9+71yA2DNAQENEgQAmeiz1+IAFMKWcpeJvwocaL2Z42x3x5Br
bA0ZDj4ESPSRi16lheSPsVX+4lS1xprnBn+kf2i3tDUcmXPFXcvA4NiZltqjdMKb
rEJjUFvYe7fsLMFuXCwXBEOQXcPKl9SVd3dXqwbT5N8ubw8RvGKKqbJz0aFThaSQ
KFKdJ6iyhAE=
=/mUB
-----END PGP SIGNATURE-----