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