Description
Using a specially crafted RTCP receiver report packet it is possible cause a Denial of Service (DoS) against Microsoft Communicator, Office Communications Server (OCS) and Windows Live Messenger.
Recommendations
Microsoft has acknowledged the issue and is working on correcting it. I n the short term it is recommended that a VoIP aware IPS product, such as VoIPguard, with signatures to detect attempts to exploit this issue, be implemented to prevent it from being exploited. Implementing best practices can limit the exposure of this issue. Microsoft customers with a valid support agreement may wish to speak with their support contact in order to obtain further vendor details.