The initial "social engineering" contest at the infamous Defcon gathering in Las Vegas shows that smooth talk may be as effective as the ability for software manipulation when it comes to mounting attacks on the computer networks of the world's biggest companies.

The competition had hackers calling employees at ten companies (which include Apple, Cisco, Microsoft and Google) to coax out information that would make it easier to mount an online attack.

"Out of all the companies called today, not one company shut us down," said Christopher Hadnagy, who is a member of the social-engineer.org team that organized the competition.

The organizers kept the competition from violating any law, however, the results show that employees may unwittingly pass on vital security information to the wrong people.

Employees who ended up having conversations with hackers ranged from a chief technical officer to IT support personnel and sales people.

Other companies targeted were Pepsi, Coca Cola, Shell, BP, Ford, and Proctor & Gamble. The winner of the contest will earn an Apple iPad tablet computer.