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AA-2006.0102                  AUSCERT Advisory

                                   [Win]
          Vulnerability in Windows Workstation Service may allow
                         remote denial of service
                             28 December 2006
- ---------------------------------------------------------------------------

        AusCERT Advisory Summary
        ------------------------

Product:              Microsoft Windows
Operating System:     Windows XP
                      Windows 2000
Impact:               Denial of Service
Access:               Remote/Unauthenticated
CVE Names:            CVE-2006-6723
Member content until: Thursday, January 25 2007

OVERVIEW

        A flaw in Windows Workstation Service handling of large RPC requests
        could allow a remote attacker to exhaust system resources leading
        to a denial of service. A proof of concept has been publicly released
        for this vulnerability.


IMPACT

        If this attack was successfully exploited the victim machine would
        devote all available processor time and memory to handling the
        malicious RPC request. This would lead to a denial of service.


MITIGATION

        At the current time there is no patch to fix this vulnerability,
        however blocking access to TCP ports 139 and 445 may protect against
        it [1]. Note that these ports may be required for file and printer
        sharing.


REFERENCES

        [1] US-CERT Current Activity
            http:/www.us-cert.gov/current/current_activity.html#mswksdos

AusCERT has made every effort to ensure that the information contained
in this document is accurate.  However, the decision to use the information
described is the responsibility of each user or organisation. The decision to
follow or act on information or advice contained in this security bulletin is
the responsibility of each user or organisation, and should be considered in
accordance with your organisation's site policies and procedures. AusCERT
takes no responsibility for consequences which may arise from following or
acting on information or advice contained in this security bulletin.

If you believe that your computer system has been compromised or attacked in 
any way, we encourage you to let us know by completing the secure National IT 
Incident Reporting Form at:

        http://www.auscert.org.au/render.html?it=3192

===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072

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 member emergencies only.
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