Warning: The use of social-networking sites such as Facebook and Twitter can lead to higher insurance premiums.

That was the conclusion of a report commissioned by U.K.-based insurance company Legal & General and prepared by reformed thief Michael Fraser, who stars in Beat the Burglar on The BBC, reports the Daily Mail.

According to the report, “The Digital Criminal,” the issues are users posting details about their homes, as well as status updates indicating that they are away from their homes. The report added that potential burglars might search for alarms or security lighting on pictures of the home, as well as dogs who might thwart their entry.

More nuggets from The Digital Criminal, which polled 2,000 social-network users: Nearly four out of 10 users posted online updates detailing their holiday plans; one in seven had seen other users’ home addresses posted on pages that could be viewed by strangers; and nearly two-thirds of 16- to 24-year-olds shared their holiday plans online.

Also, 100 friend requests were issued to strangers selected at random as an experiment, and 92% of Twitter users accepted the stranger as a friend, while only 13% of Facebook users did so.

Fraser told the Daily Mail:

There is absolutely no doubt in my mind that burglars are using social networks to identify likely targets. They gain confidence by learning more about them, what they are likely to own and when they are likely to be out of the house. I call it, “Internet shopping for burglars.” It is incredibly easy to use social-networking sites to target people, and then scope out more information on their actual home using other Internet sites like Google Street View, all from the comfort of the sofa.

Legal & General director of pricing and underwriting Malcolm Cooper told the Daily Mail:

It’s a challenging one for the insurance industry. Just because someone is burgled, you can’t prove that it’s down to details posted on Facebook.

And Privacy International director Simon Davies told the newspaper:

This is a disgraceful attempt to leverage yet more from customers.