Blocked incoming UDP traffic from an outside IP

Greetings,

We have a Windows Windows Server 2012 R2 server with SEP 12.1.6. Lookig at the Network threat Protection Traffic logs I see that it is blocking Incoming UDP traffic from an external IP. External traffic should not be getting through the firewall. Doesanyone have any ideas how to figure out how this traffic is getting to this server. According to the network engineers who maintain the firewall therre are no rules that allow this traffic to this server.

Any and all ideas are appreciated.

Joe