AUSCERT External Security Bulletin Redistribution
           ESB-1999.183 -- Microsoft Security Bulletin (MS99-053)
 Patch Available for Windows "Multithreaded SSL ISAPI Filter" Vulnerability
                              03 December 1999


Microsoft Corporation has released the following security bulletin
concerning a vulnerability in the SSL ISAPI Filter.  This vulnerability
affects the SSL ISAPI Filter shipped with  Microsoft(r) Internet
Information Server and used by other Microsoft products.

Under certain circumstances a race condition exists in multithreaded
applications which may allow a transmitting thread to send decrypted,
received data over the network.  This problem may only occur in error, 
usually under high volumes of traffic on the server.  It cannot be made 
to occur by any user.

This vulnerability may allow a malicious user to eavesdrop on another
user's plain text confidential data.  

A patch has been provided by Microsoft to eliminate this vulnerability:



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:


If you believe that your system has been compromised, contact AusCERT or
your representative in FIRST (Forum of Incident Response and Security

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