Always felt like posting your pictures and status updates? Guess you should start giving this social media habit of yours a rethink.

In Brazil, a man who admitted to kidnapping a child said he planned the crime based on details offered up by the victim’s parents on Facebook. The perpetrator, William Peterson Machado, and his girlfriend Rosicleide Roberts followed the family of the victim, Angelo Antonio (aged nine years), on the social network.

The criminals took in details of the family’s wealth by viewing photographs of a beach house, an expensive motorcycle, the latest mobilephones, designer watches and even one of the boy playing with 100-real notes. Angelo too had a profile on the social network, with pictures taken with famous models.

He was kidnapped on May 29 and a ransom demand of 600,000 reals was put up. The police later effected a rescue, but the episode has reignited the debate about the danger of social media overexposure.

“I planned all watching the kid on Facebook. I found out where he studied and what his father did. So I decided to hijack,” Peterson confessed to O Globo newspaper after his arrest.

It may be an extreme case, but anyone can be vulnerable to crimes which use personal data gleaned from the internet.

Despite pages being blocked, it was still possible to see photos of the couple using an expensive phone in the house and having lunch at upscale restaurants. Besides ostentation, the information about places and routines helped the kidnappers.

“Nobody walks into a bus with an expensive watch, but people post photos using a Facebook without realising they run a higher risk,” said Thiago Tavares, president of Safernet, a nongovernment organisation focused on protection of rights on the internet. “It is necessary to understand that the care of the real world should be extended to social networks. Information that can be used against a person must be controlled.”