I have never seen or heard of this running on a Mac.
I also had a good look at Google and couldn't find this being an issue for Mac.
Are you sure the trojan.maljava wasn't a false positive. This sounds like typical Norton scare tactics! I'm not sure of anything Robert. A box popped up during the scan and said computer was infected with that, and I clicked "repair" and it then marked it "deleted".
Nortons own site does not list this trojan effecting Mac OS.
Are you running Boot Camp, VMWare or Parallels to run Windows on your Mac? None of the above. I have no Windows anything on the Mac.
One thing you might want to do is turn on your Mac firewall, that will kill off the port scans etc, I did turn the Norton Firewall back on soon as the scan was done.