The 10,000-odd winners of MP3 players offered by McDonald's in Japan as a prize got a gift they didn't bargain for when they hooked up the devices to their PCs.

Not only did the players come with 10 pre-loaded tunes, but they also contained a nasty strain of the QQpass spyware Trojan.

In order to receive the devices, customers had to buy a large drink and submit the serial number on the container as part of a competition. Those who won received the devices and subsequently were exposed to the malware, which could allow hackers access to web passwords and other data.

After apologising, McDonald's set up a helpline to deal with the recall and to send out new devices.