[UNIX] Asterisk SIP Channel Driver Unauthenticated Calls

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Asterisk SIP Channel Driver Unauthenticated Calls
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SUMMARY

Unauthenticated calls can be made via the Asterisk SIP channel driver
using an invalid From header. This acts similarly to the SIP configuration
option 'allowguest=yes', in that calls with a specially crafted From
header would be sent to the PBX in the context specified in the general
section of sip.conf.

DETAILS

Vulnerable Systems:
* Asterisk Open Source version 1.0.x
* Asterisk Open Source versions prior to 1.2.27
* Asterisk Open Source versions prior to 1.4.18.1 and 1.4.19-rc3
* Asterisk Business Edition version A.x.x
* Asterisk Business Edition versions prior to B.2.5.1
* Asterisk Business Edition versions prior to C.1.6.2
* AsteriskNOW versions prior to 1.0.2
Asterisk Appliance Developer Kit versions prior to Asterisk 1.4 revision
109393
* s800i (Asterisk Appliance) versions prior to 1.1.0.2

Immune Systems:
* Asterisk Open Source version 1.2.27, Asterisk Open Source version
1.4.18.1 or Asterisk Open Source version 1.4.19-rc3
* Asterisk Business Edition version B.2.5.1 or Asterisk Business Edition
version C.1.6.2
* AsteriskNOW version 1.0.
* Asterisk Appliance Developer Kit version 1.4 revision 109393
* s800i (Asterisk Appliance) version 1.1.0.2

Resolution:
A fix has been added which checks for the option 'allowguest' to be
enabled before determining that authentication is not required.

As a workaround, modify the context in the general section of sip.conf to
point to a non-trusted location (example: a non-existent context, or a
context that does nothing but hang up the call).

CVE Information:
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-1332>
CVE-2008-1332


ADDITIONAL INFORMATION

The information has been provided by <mailto:jparker@xxxxxxxxxx> Jason
Parker.
The original article can be found at:
<http://downloads.digium.com/pub/security/AST-2008-003.html>
http://downloads.digium.com/pub/security/AST-2008-003.html



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