If you absolutely had to share a network with a user who had a very lax approach to security and was frequently hacked (1-2x month for over a year now), what might you consider doing to secure your own osx system, and perhaps audit the integrity of your modem/router?
The modem/router we use was recently compromised with DNS redirecting malware... and had to be replaced.
p.s. User-education is almost out of the question here, for reasons I won't get into to much... but involve, really, a completely different problem domain: human psychology. I have had no luck broaching the subject or getting access to his machine to lock it down (and this is an old old friend). I think given the hardship this person has already endured, accepting help at this point would be like admitting responsibility that he's not just a random victim... and that is hard to process.