Sooner or later, every business will have its computer system tested by a hacker.

That is the grim message from software giant Microsoft, which is holding a security summit in Auckland today.

In 2001, software developers were 331 days ahead of the hackers. By 2004 that was down to 14 days.

Seattle-based senior Security Strategist Jesper Johannson says the hackers are getting quicker and quicker at developing viruses and software which attack networks. He says they are working to mitigate as much of that risk as possible and minimise what they cannot mitigate.

He says by building layers of security, it is possible to build a defence against an attack which has not even been thought of yet.

Microsoft's chief technology officer, Brett Roberts, says the trick to defending a company's software and hardware, is to educate the work force.