DOCUMENT:Q307195 08-MAY-2002 [exchange] TITLE :XWEB: Unauthenticated User Can Enumerate Global Address List PRODUCT :Microsoft Exchange PROD/VER::5.5,5.5 SP1,5.5 SP2,5.5 SP3,5.5 SP4 OPER/SYS: KEYWORDS:kbSecurity kbExchange550preSP5fix KbSECVulnerability KbSECHack ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Exchange Server, versions 5.5, 5.5 SP1, 5.5 SP2, 5.5 SP3, 5.5 SP4 ------------------------------------------------------------------------------- SYMPTOMS ======== An information disclosure vulnerability exists in Exchange Server 5.5 that an Internet-based attacker can use to learn the e-mail addresses of users on a corporate Exchange Server 5.5 computer if the server is configured to offer Microsoft Outlook Web Access (OWA). The vulnerability does not allow the attacker to read, write, or change any of the users' e-mail, or to take any other action against the users. The vulnerability also does not allow the attacker to gain any privileges on the server. The vulnerability's sole effect is to allow the attacker to learn the e-mail names of users on the server. This vulnerability does not affect Microsoft Exchange 2000 Server. CAUSE ===== This problem can occur because a function in OWA that queries the Global Address List does not require authentication. Unauthenticated users can call the function and enumerate the mail addresses of users on the server. RESOLUTION ========== A supported fix is now available from Microsoft, but it is only intended to correct the problem described in this article and should be applied only to systems that are determined to be at risk of attack. Please evaluate your computer's physical accessibility, network and Internet connectivity, and other factors to determine the degree of risk to your computer. Please see the associated Microsoft Security Bulletin (http://www.microsoft.com/technet/security/bulletin/MS01-047.asp) to help make this determination. This fix may receive additional testing at a later time, to further ensure product quality. If your computer is sufficiently at risk, Microsoft recommends that you apply this fix now. Otherwise, wait for the next Microsoft Exchange Server 5.5 service pack that contains this fix. To resolve this problem immediately, download the fix as instructed below or contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web: http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS NOTE: In special cases, charges that are normally incurred for support calls may be canceled, if a Microsoft Support Professional determines that a specific update will resolve your problem. Normal support costs will apply to additional support questions and issues that do not qualify for the specific update in question. The following file is available for download from the Microsoft Download Center: DownloadDownload Q307195engi386.exe now (http://www.microsoft.com/Downloads/Release.asp?ReleaseID=32483) NOTE: This patch can be applied to any language version. Release Date: September 6, 2001 For additional information about how to download Microsoft Support files, click the article number below to view the article in the Microsoft Knowledge Base: Q119591 How to Obtain Microsoft Support Files from Online Services Microsoft used the most current virus detection software available on the date of posting to scan this file for viruses. After it is posted, the file is housed on secure servers that prevent any unauthorized changes to the file. The English version of this fix should have the following file attributes or later: Component: OWA +---------------------+ | File name | Version | +---------------------+ | Fumsg.asp | NA | +---------------------+ NOTE: Because of file dependencies, this fix requires Microsoft Exchange Server version 5.5 Service Pack 4. STATUS ====== Microsoft has confirmed that this problem could result in some degree of security vulnerability in Microsoft Exchange Server version 5.5. MORE INFORMATION ================ For more information on this vulnerability, see the following Microsoft Web site: http://www.microsoft.com/technet/security/bulletin/MS01-047.asp Additional query words: security_patch GAL ====================================================================== Keywords : kbSecurity kbExchange550preSP5fix KbSECVulnerability KbSECHack Technology : kbExchangeSearch kbExchange550 kbZNotKeyword2 kbExchange550SP1 kbExchange550SP2 kbExchange550SP3 kbExchange550SP4 Version : :5.5,5.5 SP1,5.5 SP2,5.5 SP3,5.5 SP4 Issue type : kbbug Solution Type : kbfix ============================================================================= 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. Copyright Microsoft Corporation 2002.