Cyber security expert Jeff Whitton said the internet's dark web, where everything is up for sale, is a threat to hundreds of Central West businesses.

The CEO of Knet Technology said businesses as varied as mining companies and medical centres are vulnerable unless security is policed within the workplace.

Mr Whitton, who is also an Orange City councillor, said one of the greatest vulnerabilities is "the password problem".

"Computer users feel burdened by the constant demand for passwords and resort to using the same letter/number combinations across multiple private and work accounts," Mr Whitton said.

"It's a gold embossed invitation for a criminal. In a data breach, those passwords are up for sale in a flash on the dark web."

Mr Whitton said it's important not to leave security protection to employees or even office managers.

"We need CEOs and business owners and directors to take responsibility, understand the risks and manage tighter control of their cyber security.

"The seminar will give them the tools to do this and prevent local organisations falling victim to salesmen on the dark web where passwords and email addresses are a lucrative business."

The Cyber Security and Data Breaches Lunch and Learn will talk place from 12-1pm.

To RSVP visit: www.knet.events or phone 02 6363 8999.