Greg Boyle, from Trend Micro, said putting financial or personal information out on social media networks was the same as handing it out in public.
"If you wouldn't stand up on the bus to tell people, don't share it on social media."
Boyle said New Zealanders were highly security conscious on the one hand, but on the other were continuing to share private details publically.
People should never write down their pin, bank account details or password but should instead do it verbally, he said.
"The minute you write it down, you increase the risk of someone getting access to that information. Speak over the phone or go to the pub and pass it on over a beer."
The survey found New Zealanders had an average of 12 different online accounts but only eight passwords.
Having a different password for each account was crucial because once someone gained access to one account, they could gain access to others, Boyle said.
One way of developing a strong password was to think of a memorable sentence, then choose the first letter from every word to form a sequence. Change some letters into numbers to make it more secure, he said.
Social media users should also check their privacy settings to make sure they were only sharing information with friends - and do not accept random friend requests.
Meanwhile, another study has found large numbers of Facebook users are deleting their accounts because of privacy concerns.
An investigation into the phenomenon of "virtual identity suicide" identified privacy as the biggest reason people are turning against the social network giant.
Data protection issues, social pressure to add friends, fears of internet addiction, shallow conversations, and loss of interest in the site were among the reasons for leaving.
