This indicates an attack attempt against a denial-of-service vulnerability in the Pragmatic General Multicast (PGM) protocol on Microsoft Windows.
The vulnerability is caused by an error when the vulnerable software handles malformed PGM fragmented packets received. It allows a remote attacker to cause a denial-of-service condition by sending specially crafted PGM packets.
Windows XP SP2
Windows XP SP3
Windows XP Professional x64 Edition and SP2
Windows Server 2003 SP1 and SP2
Windows Server 2003 x64 Edition and SP2
Windows Server 2003 with SP1 for Itanium-based Systems and SP2
Windows Vista and Windows Vista Service Pack 1
Windows Vista x64 Edition and Windows Vista x64 Edition Service Pack 1
Windows Server 2008 for 32-bit Systems
Windows Server 2008 for x64-based Systems
Windows Server 2008 for Itanium-based Systems
Denial of service
Please see the Microsoft advisory for the patch or update: