[NT] Microsoft Windows CE IGMP Denial of Service

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Microsoft Windows CE IGMP Denial of Service
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SUMMARY

This issue was originally discovered by Douglas Nascimento of Datacom and
published in Microsoft security bulletin MS06-007 on February 14th 2006
and subsequently updated March 17th 2006. A condition exists with the
Microsoft IP stack wherein a specially crafted IGMP packet causes a denial
of service condition. In Microsoft's original advisory, Windows CE was
omitted as a vulnerable platform; however, In Symantec's testing it was
discovered that Windows CE 5.01 (shipped as part of the Windows Mobile 5
PocketPC and SmartPhone editions) is vulnerable. Symantec notified
Microsoft in Feburary 2006 of the fact that CE was affected with Microsoft
releasing a patch in KB930642 in February 2007.

DETAILS

Vulnerable Systems:
* Windows CE version 5.01 / Windows Mobile 5

On the day of release Symantec developed a working trigger for this
vulnerability. A public exploit for this issue was released by Alexey
Sintsov on the 21st of March 2006. When an IGMP packet is supplied with
invalid IP options then it will cause a denial of service condition. As
IGMP can be sent both via unicast and mulicast it is possible to cause the
issue to manifest itself in many devices with a single packet if
appropriate network filtering is not in place.

Vendor Response:
There is a security vulnerability that could allow for Denial of Service
(DoS) by sending a specifically crafted TCP/IP packet to the mobile
device. However most attempts to exploit this vulnerability would result
in a Denial of Service Condition on the networking capabilities of the
device.

The following devices may be vulnerable to this issue:

* Windows CE 4.2 - Windows CE .NET 4.2 Platform Builder Monthly Update
(September 2007)
* Windows Mobile 5.0 - A fix for this issue has been provided by
Microsoft via

http://support.microsoft.com/kb/930642

(Fixed in Windows Mobile 6.0)

Recommendation:
Windows Mobile 5.0 customers please see your handset manufacturer to
obtain the update customized for your device to Windows Mobile 6.

OEMs which utilise Windows CE should ensure KB930642 is applied to their
build environment. Details can be found here on Microsoft's support site -
<http://support.microsoft.com/kb/930642/>

http://support.microsoft.com/kb/930642/.

Carriers should ensure appropiate network filtering is in place in order
to protect affected handsets.

CVE Information:
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-0021>
CVE-2006-0021

ADDITIONAL INFORMATION

The information has been provided by
<mailto:ollie_whitehouse@symantec.com> Ollie Whitehouse.

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