Lucene search

K
securityvulnsSecurityvulnsSECURITYVULNS:DOC:3776
HistoryNov 21, 2002 - 12:00 a.m.

Microsoft Security Bulletin MS02-065: Buffer Overrun in Microsoft Data Access Components Could Lead to Code Execution (Q329414)

2002-11-2100:00:00
vulners.com
53

-----BEGIN PGP SIGNED MESSAGE-----


Title: Buffer Overrun in Microsoft Data Access Components Could
Lead to Code Execution (Q329414)
Date: 20 November, 2002
Software:
Microsoft Data Access Components (MDAC) 2.1
Microsoft Data Access Components (MDAC) 2.5
Microsoft Data Access Components (MDAC) 2.6
Microsoft Internet Explorer 5.01
Microsoft Internet Explorer 5.5
Microsoft Internet Explorer 6.0
Impact: Run code of attacker?s choice
Max Risk: Critical
Bulletin: MS02-065

Microsoft encourages customers to review the Security Bulletins at:
http://www.microsoft.com/security/security_bulletins/ms02-065.asp
http://www.microsoft.com/technet/security/bulletin/MS02-065.asp.


Issue:

Microsoft Data Access Components (MDAC) is a collection of components
used to provide database connectivity on Windows platforms. MDAC is
a ubiquitous technology, and it is likely to be present on most
Windows systems:

    • It is included by default as part of Windows XP, Windows 2000, and
      Windows Millennium.
    • It is available for download as a stand-alone technology in its
      own right.
    • It is either included in or installed by a number of other products
      and technologies. For instance, MDAC is included in the Windows NT
      4.0 Option Pack, and some MDAC components are present as part of
      Internet Explorer even if MDAC itself is not installed.

MDAC provides the underlying functionality for a number of database
operations, such as connecting to remote databases and returning data
to a client. One of the MDAC components, known as Remote Data
Services(RDS), provides functionality that support three-tiered
Architectures ? that is, architectures in which a client?s requests
for service from a back-end database are intermediated through a web
site that applies business logic to them. A security vulnerability
is present in the RDS implementation, specifically, in a function
called the RDS Data Stub, whose purpose it is to parse incoming
HTTP requests and generate RDS commands.

The vulnerability results because of an unchecked buffer in the Data
Stub. By sending a specially malformed HTTP request to the Data Stub,
an attacker could cause data of his or her choice to overrun onto the
heap. Although heap overruns are typically more difficult to exploit
than the more-common stack overrun, Microsoft has confirmed that in
this case it would be possible to exploit the vulnerability to run
code of the attacker?s choice on the user?s system.

Both web servers and web clients are at risk from the vulnerability:


    • Web servers are at risk if a vulnerable version of MDAC is
      installed
      and running on the server. To exploit the vulnerability against
      such
      a web server, an attacker would need to establish a connection with
      the server and then send a specially malformed HTTP request to it,
      that would have the effect of overrunning the buffer with the
      attacker?s chosen data. The code would run in the security context
      of the IIS service (which, by default, runs in the LocalSystem
      context)
    • Web clients are at risk in almost every case, as the RDS Data Stub
      is included with all current versions of Internet Explorer and
      there is no option to disable it. To exploit the vulnerability
      against a client, an attacker would need to host a web page that,
      when opened, would send an HTTP reply to the user's system and
      overrun the buffer with the attacker's chosen data. The web page
      could be hosted on a web site or sent directly to users as an HTML
      Mail. The code would run in the security context of the user.

Clearly, this vulnerability is very serious, and Microsoft recommends
that all customers whose systems could be affected by them take app-
ropriate action immediately. Web server administrators should either
install the patch, disable MDAC and/or RDS, or upgrade to MDAC 2.7,
which is not affected by the vulnerability. Web client users should
install the patch immediately on any system that is used for web
browsing. It is important to stress that the latter guidance applies
to any system used for web browsing, regardless of any other
protective measures that have already been taken. For instance, a
web server on which RDS had been disabled would still need the patch
if it was occasionally used as a web client.

Mitigating Factors:

Web Servers

    • Web servers that are using MDAC version 2.7 (the version that
      shipped with Windows XP) or later are not affected by the vulner-
      ability.
    • Even if a vulnerable version of MDAC were installed, a web server
      would only be at risk if RDS were enabled. RDS is disabled by
      default
      on clean installations of Windows XP and Windows 2000, and can be
      disabled on other systems by following the guidance in the IIS
      Security Checklist. In addition, the IIS Lockdown Tool will
      automatically disable RDS when used in its default configuration.
    • If the URLScan tool were deployed with its default ruleset (which
      allows only ASCII data to be present in an HTTP request), it is
      likely that the vulnerability could only be used for denial of
      service attacks.
    • IIS can be configured to run with fewer than administrative priv-
      ileges. If this has been done, it would likewise limit the
      privileges
      that an attacker could gain through the vulnerability.
    • IP address restrictions, if applied to the RDS virtual directory,
      could enable the administrator to restrict access to only trusted
      users. This is, however, not practical for most web server
      scenarios.

Web clients

    • The HTML mail-based attack vector could not be exploited auto-
      matically on systems where Outlook 98 or Outlook 2000 were used
      in conjunction with the Outlook Email Security Update, or Outlook
      Express 6 or Outlook 2002 were used in their default
      configurations.
    • Exploiting the vulnerability would convey to the attacker only the
      user?s privileges on the system. Users whose accounts are
      configured
      to have few privileges on the system would be at less risk than
      ones who operate with administrative privileges.

Risk Rating:

  • Internet systems: Critical
  • Intranet systems: Critical
  • Client systems: Critical

Patch Availability:

Acknowledgment:


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 7.1

iQEVAwUBPdvJ8I0ZSRQxA/UrAQER+wgAj6UQfMzv8Ydv4ZuZVuQS0CHiVQ+r8Ykm
kDZ/EQhmDo7/j+SXVqGjvycrZCGFET5guGbrGzc7z4bQFAQMs2YxbOxhDYirCxQ6
9zsRDuUkmztjY7VB+oeWBIgaENcFPfv0v9XOMN8pArr1PziHaKOeZ+pYkoFvM83t
IegB6sRw6dc8UfvC0j5eyCnW+YXrRgWjAq3KCn+TW7dVgGSCONUXtwXPxzEivk21
zcNu8pOWY7z49zOLJKJlad78XiraUvhUNj1IGM0J5/XhRHsVe1MI3+V8Btsx0EGo
XwwHx8Zua0l4n/XMufIr5Zr0jhNH9KO2jABDvDCEw3ofGeYo/mJgZw==
=CYOd
-----END PGP SIGNATURE-----


You have received this e-mail bulletin because of your subscription to the Microsoft
Product Security Notification Service. For more information on this service, please visit
http://www.microsoft.com/technet/security/notify.asp.

To verify the digital signature on this bulletin, please download our PGP key at
http://www.microsoft.com/technet/security/notify.asp.

To unsubscribe from the Microsoft Security Notification Service, please visit the Microsoft
Profile Center at http://register.microsoft.com/regsys/pic.asp

If you do not wish to use Microsoft Passport, you can unsubscribe from the Microsoft
Security Notification Service via email as described below:
Reply to this message with the word UNSUBSCRIBE in the Subject line.

For security-related information about Microsoft products, please visit the Microsoft
Security Advisor web site at http://www.microsoft.com/security.