Officials are forensically investigating the cause of the cyber attack afflicting the Waikato District Health Board.

A DHB spokesperson says the working theory is the attack happened as a result of someone opening an email attachment.

The entire District Health Board's IT services were brought down by hackers yesterday, affecting clinical services across all of its hospitals.

Gorilla Technology Chief Executive Paul Spain joined Simon Barnett and Phil Gifford to discuss cyber-security vulnerability.

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