Published:
06 September 2001
Protect yourself against future threats.
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AUSCERT External Security Bulletin Redistribution
ESB-2001.384 -- Microsoft Security Bulletin MS01-047
OWA Function Allows Unauthenticated User to Enumerate Global Address List
7 September 2001
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AusCERT Security Bulletin Summary
---------------------------------
Product: Exchange 5.5
Vendor: Microsoft
Impact: Access Privileged Data
Access Required: Remote
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Title: OWA Function Allows Unauthenticated User to Enumerate
Global Address List
Date: 06 September 2001
Software: Exchange 5.5
Impact: Information Disclosure
Bulletin: MS01-047
Microsoft encourages customers to review the Security Bulletin at:
http://www.microsoft.com/technet/security/bulletin/MS01-047.asp.
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Issue:
======
Among the functions Outlook Web Access (OWA) in Exchange 5.5 offers
is the ability to search the global address list (GAL). By design,
this is an authenticated function, implemented as a two-tier
architecture - a front tier that provides a user interface and a
back-end tier that actually performs the search. However, only the
front tier actually checks authentication. An attacker who sent a
properly formatted request to the back-end function that actually
performs the search could enumerate the GAL without authenticating.
Mitigating Factors:
====================
- The vulnerability would only allow the attacker to learn
users' email aliases. It would not provide any other
capabilities. Specifically, it would not give the attacker
any way to create or send mail as a user; to read, change
or delete mail; or to perform any other functions on the
server.
- The vulnerability is only exploitable via OWA. Exchange
servers that are not configured to offer OWA are not affected
by the vulnerability.
- The vulnerability does not affect Exchange 2000, even when
offering OWA.
Patch Availability:
===================
- A patch is available to fix this vulnerability. Please read the
Security Bulletin at
http://www.microsoft.com/technet/security/bulletin/ms01-047.asp
for information on obtaining this patch.
Acknowledgment:
===============
- Noam Rathaus from SecuriTeam.com (http://www.SecuriTeam.com)
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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.
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