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TUCoPS :: Windows Net Apps :: ciacm040.txt

MS Exchange - Incorrectly Sets Remote Registry Permissions

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M-040: MS Exchange - Incorrectly Sets Remote Registry Permissions

[Microsoft Security Bulletin MS02-003]

February 8, 2002 18:00 GMT
 PROBLEM:           There is a flaw in how the System Attendant makes
                    changes to the Registry configuration.
 PLATFORM:          Microsoft Exchange Server 2000
 DAMAGE:            This flaw could allow an attacker remote access to
                    configuration information on the server.
 SOLUTION:          Apply available patch.
 VULNERABILITY      The risk is LOW. This vulnerability does not itself
 ASSESSMENT:        give an attacker the ability to change Registry
                    settings. It could be used in conjunction with
                    inappropriately permissive registry settings to gain
                    access to, and make changes to a systems Registry.


[***** Start Microsoft Security Bulletin MS02-003 *****]

Microsoft Security Bulletin MS02-003

Exchange 2000 System Attendant Incorrectly Sets Remote Registry Permissions
Originally posted: February 07, 2002


Who should read this bulletin: System administrators using Microsoft®
Exchange 2000.

Impact of vulnerability: Less Secure Default Settings.

Maximum Severity Rating: Low

Recommendation: Administrators should apply the patch.

Affected Software:

   * Microsoft Exchange Server 2000

Technical details

Technical description:

The Microsoft Exchange System Attendant is one of the core services in
Microsoft Exchange. It performs a variety of functions related to the
on-going maintenance of the Exchange system. To allow remote administration
of an Exchange Server using the Exchange System Manager Microsoft Management
Console (MMC) snap in, the System Attendant makes changes to the permissions
on the Windows Registry to allow Exchange Administrators to remotely update
configuration settings stored in the Registry.

There is a flaw in how the System Attendant makes these Registry
configuration changes. This flaw could allow an unprivileged user to remotely
access configuration information on the server. Specifically, this flaw
inappropriately gives the "Everyone" group privileges to the WinReg key. This
key controls the ability of users and groups to remotely connect to the
Registry. By default, only Administrators are given the ability to remotely
connect to the Registry, by granting permissions on this key.

The flaw does not grant any abilities beyond the ability to connect remotely.
However, an attacker's ability to make changes to the Registry once they have
successfully connected would be dictated by the permissions on the specific
keys within the Registry itself. Thus, while this vulnerability does not
itself give an attacker the ability to change Registry settings, it could be
used in conjunction with inappropriately permissive registry settings to gain
access to, and make changes to a systems Registry.

Mitigating factors:

   * The vulnerability only grants the ability to connect to the Registry remotely.
     It does not weaken any other permissions in the Registry.

   * An attacker's ability to connect to the Registry remotely requires the ability
     to send SMB traffic to and from the target system. Firewalling best practices
     recommends closing the ports that NetBIOS and Direct Host uses (tcp ports 139 and 445)

Severity Rating:

                        Internet Servers   Intranet Servers     Client Systems
Exchange 2000 Server    Low                Low                  None

The above assessment is based on the types of systems affected by the
vulnerability, their typical deployment patterns, and the effect that exploiting
the vulnerability would have on them. For Internet exposed systems, the best
practices of blocking tcp ports 139 and 445 at the firewall prevents remote
access to the registry. While there is a potential for allowing data to be
compromised, there are significant mitigating factors.

Vulnerability identifier: CAN-2002-0049

Tested Versions:
Microsoft tested Exchange 5.5 and Exchange 2000 to assess whether they are
affected by these vulnerabilities. Previous versions are no longer supported,
and may or may not be affected by these vulnerabilities.

Patch availability

Download locations for this patch

   * Microsoft Exchange Server 2000:

Additional information about this patch

Installation platforms:
This patch can be installed on systems running Microsoft Exchange 2000 SP2.

Inclusion in future service packs:
The fix for this issue will be included in Microsoft Exchange 2000 SP3.

Reboot needed: Yes
Superseded patches: None.

Verifying patch installation:

   * To verify that the patch has been installed on the machine, confirm that the
     following registry key has been created on the machine:
     HKEY_LOCAL_MACHINE\Software\Microsoft\Updates\Exchange Server 2000\SP3\Q316056.
   * To verify the individual files, use the date/time and version information
     provided in the following registry key: HKEY_LOCAL_MACHINE \Software\Microsoft\
     Updates\Exchange Server 2000\SP3\Q316056\filelist


Localized versions of this patch are under development. When completed, they will
be available at the locations discussed in "Obtaining other security patches".

Obtaining other security patches:
Patches for other security issues are available from the following locations:

   * Security patches are available from the Microsoft Download Center, and can be
     most easily found by doing a keyword search for "security_patch".

   * Patches for consumer platforms are available from the WindowsUpdate web site

   * All patches available via WindowsUpdate also are available in a redistributable
     form from the WindowsUpdate Corporate site.

Other information:


Microsoft thanks Eitan Caspi for reporting this issue to us and working with us
to protect customers.


   * Microsoft Knowledge Base article Q316056 discusses this issue and will be
     available approximately 24 hours after the release of this bulletin. Knowledge
     Base articles can be found on the Microsoft Online Support web site.

   * Technical support is available from Microsoft Product Support Services. There is
     no charge for support calls associated with security patches.

Security Resources: The Microsoft TechNet Security Web Site provides additional
information about security in Microsoft products.

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.


   * V1.0 (February 07, 2002): Bulletin Created.

[***** End Microsoft Security Bulletin MS02-003 *****]

CIAC wishes to acknowledge the contributions of Microsoft for the
information contained in this bulletin.
CIAC services are available to DOE, DOE Contractors, and the NIH. CIAC can
be contacted at:

    Voice:          +1 925-422-8193 (7 x 24)
    FAX:            +1 925-423-8002
    STU-III:        +1 925-423-2604
    World Wide Web:
                     (same machine -- either one will work)
    Anonymous FTP:
                     (same machine -- either one will work)

This document was prepared as an account of work sponsored by an agency of
the United States Government. Neither the United States Government nor the
University of California nor any of their employees, makes any warranty,
express or implied, or assumes any legal liability or responsibility for
the accuracy, completeness, or usefulness of any information, apparatus,
product, or process disclosed, or represents that its use would not
infringe privately owned rights. Reference herein to any specific
commercial products, process, or service by trade name, trademark,
manufacturer, or otherwise, does not necessarily constitute or imply its
endorsement, recommendation or favoring by the United States Government or
the University of California. The views and opinions of authors expressed
herein do not necessarily state or reflect those of the United States
Government or the University of California, and shall not be used for
advertising or product endorsement purposes.
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