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              AUSCERT External Security Bulletin Redistribution
                             
           ESB-1999.111 -- Microsoft Security Bulletin (MS99-029)
      Patch Available for "Malformed HTTP Request Header" Vulnerability
                               12 August 1999

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Microsoft Corporation has released the following security bulletin
concerning a malformed HTTP request header vulnerability in IIS 4.0.  This
vulnerability lies in the fact that IIS creates and extends its log file
in 64KB increments and that the trigger to extend is an attempt to write
a record larger than the remaining space in the increment.  If a record
is written to the log file so that it ends exactly on a 64Kb boundary, an
error in the software causes the web sever to hang. This may allow denial
of service attacks against IIS:

       http://www.microsoft.com/security/bulletins/ms99-029regression.asp
       http://www.microsoft.com/security/bulletins/ms99-029.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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