How much do your online friends know about you? When you’re hitting up Facebook, Pinterest, Google, or any other social service, how many friends do you actually trust? A new survey has shown that we’re a tad too trusting with personal information.

According to new survey conducted on behalf of Norton, Australians are spending an average of 11.6 hours per week on social networks, with roughly half of us having no privacy settings selected.

While security settings aren’t the be all and end all of our online lives, many of us are adding “friends” that we don’t know or don’t trust, with one in four opening up their lives to people who could potentially be dangerous.

“People can be quite naïve as to how useful their personal information is to cyber-criminals,” said Alastair MacGibbon, the Director of the Centre for Internet Safety at the University of Canberra. “That information can be used to help uncover passwords, or answer those common ‘security questions’ like a first pet or your mother’s maiden name to reset a password and give them access. The trouble is that we can expose the clues or answers, the more we share online.”

We’ve said in the past how insecure passwords can be, with many people opting to use their first name, last name, and birthday, as well as the names of favourite superheroes or the word “password”, but it goes deeper than this. Password reset systems generally rely on simple questions relating to things about your life that only you may know, but with social networking, we may also be sharing those little things.

If the reset question on your email is, for instance, “what is your mother’s maiden name” and your mother is a friend of yours on Facebook, a potential attacker can gain access to that quite easily, especially if they’ve been added to your friend list without you realising who it is.

Once the attacker has compromised your email, they potentially have access to everything, locking you out.

“This sort of cybercrime happens often and social networking sites give criminals plenty of opportunities to exploit,” said Mr. MacGibbon. “Most criminals are motivated by money, so they primarily look for your credit card, financial or banking details. However, your social network and connections or email can be useful to reach out to your friends and trick them into sharing those details as well.  That’s potentially damaging for you and your friends.”

Norton’s Internet Safety Advocate, Michele Thompson, suggests that users “think twice before adding in milestones, photos, and past stories of yourself or your family,” as these can be used against you as a knowledge source. “Think about whether you’re giving away any answers to common security questions such as your mother’s maiden name, favourite pet or the street you lived on as a child.”

Security software also helps, as does checking your privacy and security settings on the various networks, but it’s always good to be aware just who you’re adding to your online life.