Problem with malicious Traffic in my MacBook
The malware may be transmissible by macs, it's uncertain.  Regardless, you might, in addition to checking DHCP:


Ensure that your search domains in Directory Utility are not set to "Automatic", which will leave you open to rogue DHCP servers on your network.
Consider arpsniff or ArpSpyX or some modern equivalent. Those rogues would gain access possibly via ARP poisoning ( google that)
Little Snitch or some other application firewall would be useful here as well.
Turn off Xgrid, in fact, turn off sharing unless you are using it.