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AA-2008.0257                  AUSCERT Advisory

                               [UNIX/Linux]
        A vulnerability has been identified in Asterisk Open Source
                       and Asterisk Business Edition
                             19 December 2008
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        AusCERT Advisory Summary
        ------------------------

Product:              Asterisk Open Source 1.2.26 through 1.2.30.3
                      Asterisk Business Edition B.2.3.5 through B.2.5.5
Operating System:     UNIX variants (UNIX, Linux, OSX)
Impact:               Denial of Service
Access:               Remote/Unauthenticated
CVE Names:            CVE-2008-5558
Member content until: Friday, January 09 2009

Revision History:     December 19 2008: Added CVE
                      December 12 2008: Initial Release

OVERVIEW:

      A vulnerability has been identified in Asterisk Open Source 1.2.26 
      through 1.2.30.3 and Asterisk Business Edition B.2.3.5 through B.2.5.5.


IMPACT:

      This vulnerability which can cause a denial of service on "... an 
      Asterisk server if the server is configured to use realtime IAX2 users. 
      The issue occurs if either an unknown user attempts to authenticate or 
      if a user that uses hostname matching attempts to authenticate." [1]


MITIGATION:

      The vendor recommends upgrading to the latest version of Asterisk
      Open Source and Asterisk Business Edition respectively. [1]


REFERENCES:

      [1] Asterisk Project Security Advisory - AST-2008-012
          http://downloads.digium.com/pub/security/AST-2008-012.html

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

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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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