"Targeted Hacking Forces a New Reality on Antivirus Companies"
Article here.
A recent study by Imperva, a California data security startup, found that antivirus products from top vendors detected less than 5 percent of more than 80 new viruses tested.
...Rather than using a blacklist to block known threats—the conventional method employed by antivirus software—FireEye works by assuming everything is suspect and testing programs in a safe “sandbox” before allowing them to run on a machine.