Symantec alerted an attack: OSX Apple File Print Remote BO from TimeMachine
It's not necessarily a false alarm - the endpoint protection application is just looking for a packet that's addressed to a certain port and formed a certain way.

192.168.200.248 is a Time Machine device, so it very well could just be talking in a way that the EP program doesn't like, but it is possible, albeit very unlikely, that the time machine is compromised being used by an attacker as a foothold into your network. Are you getting any other alerts? If not, I think you can write this off as nonsense. Especially given the age of the vulnerability.

(Network security is great for ramping up your paranoia...)

In any case, even if you didn't have the endpoint protection, it's not a danger to you. This bug was fixed back in 2004 - no system from the last decade is even vulnerable to it.