We have noticed a surge in traffic on port 12345. This could be NetBus, or a variant. We suspect that some trojan backdoor is in the wild tacked on to a new worm. The worm is looking for other friendly hosts listening on port 12345. To see a historical chart of activity on this port, see this page. Do patch up your systems. Also, run a scan of your network yourself to see if port 12345 is listening anywhere.