At this point, Macs are still very secure..
That intego article is flawed in it's wording ( likely to sell more virus software, considering they write mac anti-virus software) .. even if your settings on your browser are set to automatically run the DMG file, the actual application will still NOT autorun..that part is impossible.
it's basically like the old school codec tricks you'd find 10 years ago on windows.
Once they figure out how to autorun a program, there will be a real threat.. but at this time it's impossible ( and would still need a root password ) hence my suggestion to change that setting in safari to mount DMG's automatically and run in a non admin account
My point was at very best this is a bad program, not a virus.