I could not find a specific forum on this topic,I hope some here can help. Over the weekend I received calls from 2 credit card companies indicating that several high dollar purchases had been made,some outside the U.S. These were fraudulent charges. The 2 credit cards were never used on any site together. I am racking my brain on where they could get both numbers,regardless I would like to add security to my IMac and protect it as much as possible in the event it has been hacked. Any recommendations of the best Mac security is greatly appreciated. Thank you for your time and comments in advance.