It seems an unlikely venue for high-tech criminality, but police and internet companies are warning of a new wave of wi-fi crime following two incidents in Worcestershire.

Twice in the past month, officers from West Mercia Police have been called to the Redditch suburbs after residents reported a suspicious individual sitting in a parked car with an open laptop.

Both individuals, a man and a woman, were apparently connecting to a nearby home-owner’s wireless internet connection, in a practice known as “piggy-backing”.

The incidents were apparently unconnected: less a criminal network than two cases of criminal networking. But both were arrested and cautioned for dishonestly obtaining electronic communications services with intent to avoid payment.

PC Tony Humphreys said: “We want people to be aware that this is possible and to be vigilant regarding their own broadband connections.

“Wireless networks don’t stop at the walls of your home, and without protection, your neighbours or people in the road outside may be able to connect to your network.”

This was once thought a victimless offence: the purchaser of a wireless connection typically pays a fixed rate and the connection speed would be only marginally slowed by a stranger hitching a ride.

However, wireless providers and internet security firms have warned that wi-fi “piggy-backing” can provide a useful gateway for criminal activity.

The wi-fi provider The Cloud said: “A lot of people don’t realise they have to activate their security so their system is password protected.

“When they don’t do this, anyone can walk up outside their house and access their network. A computer hacker can then quite easily access your computer and any personal information on it provided it is turned on.”

In the US in 2004, Brian Salcedo, 21, was sentenced to nine years in prison for siphoning credit card numbers over a wireless network from a shop.

There are also fears that unprotected wi-fi networks could allow criminals to download pornography or launch viruses and implicate an innocent wi-fi subscriber.

PC Humphreys said: “We don’t want to alarm users. We want them to follow the advice on wireless broadband security issued by their broadband providers.”

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