Wireless security consultants Orthus carried the research at three mainline train stations in London, England and found that 49 percent of Bluetooth device owners were vulnerable to "Bluesnarfing" - having their calls hijacked or personal data such as photos, SMS messages or phonebook contacts stolen.
The survey also found that the majority of Bluetooth users that took their devices off "default" status gave them unusual names and invited other Bluetooth users to connect and chat. This activity (known as "Toothing") also opened up their devices to potential hacking. The survey also found hundreds of strangely named devices ranging from "Love Monkey" to "Call me Pickles".
An engineer armed with a laptop and a Linux-based security tool was able to identify hundreds of devices left unsecured as commuters tmade their way home through the stations.
The engineer also found that 379 out of 943 devices identified were still set to their default security settings and 138 of the 943 were vulnerable to hacking.
Martin Allen, managing director of mobile data security company Pointsec, said Bluesnarfing was a "silent threat which you wouldn't even know is happening to you."
"People keep a lot of confidential information on their PDAs and mobiles such as passwords, pin numbers, bank account details, customers names and addresses and within seconds this can be pulled by a hacker or competitor from right under their nose," he said.
He urged companies to to make sure that if staff have sensitive information on their mobile devices that "it is encrypted centrally and mandated within the security policy."
Earlier this month, SC Magazine reported on a mobile phone virus that can infect PCs.