Patch Available to Improve TCP Initial Sequence Number Randomness

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              AUSCERT External Security Bulletin Redistribution
                             
    ESB-1999.201 -- Re-release of Microsoft Security Bulletin (MS99-046)
      Patch Available to Improve TCP Initial Sequence Number Randomness
                              24 December 1999

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Microsoft Corporation has re-released the following security bulletin
concerning a vulnerability in the randomness of TCP initial sequence
numbers of the Microsoft TCP/IP stack.

On 25 October 1999 AusCERT released ESB-1999.163 encapsulating the Microsoft 
Security Bulletin (MS99-046).  Microsoft subsequently withdrew the patch 
associated with Bulletin (MS99-046) in November 1999 and have now 
re-released the updated bulletin and patch for the vulnerability.

All Microsoft Windows NT 4.0 platforms are affected by this vulnerability.

This vulnerability may allow IP address spoofing attacks and network
sessions to be hijacked.

Microsoft has re-issued the patch which corrects this vulnerability:

       http://www.microsoft.com/security/bulletins/MS99-046.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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