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              AUSCERT External Security Bulletin Redistribution
                             
           ESB-1999.108 -- Microsoft Security Bulletin (MS99-027)
        Patch Available for "Encapsulated SMTP Address" Vulnerability
                               09 August 1999

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Microsoft Corporation has released the following security bulletin
concerning a security vulnerability in Microsoft Exchange Server.

Exchange server implements features designed to defeat "mail
relaying" but a vulnerability in this anti-relaying feature allows
encapsulated SMTP addresses to be interpreted by SMTP to achieve
the same effect.

This vulnerability could allow an attacker to perform mail relaying
via an Exchange server that is configured to act as a gateway for
other Exchange sites using the Internet Messaging Service:

       http://www.microsoft.com/security/bulletins/MS99-027.asp


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This security bulletin is provided as a service to AusCERT's members.
As AusCERT did not write the document referenced 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.

If you have any questions or need further information, please contact 
Microsoft Corporation 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.

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