TOKYO: Fast food and worms are never a good mix. Especially when the intruder is of the software kind and the restaurant chain is McDonald's.

The hamburger purveyor to the planet is counting the cost of a promotional competition run through its Japanese outlets.

Ten thousand consumers won free MP3 music players plus songs. The unwelcome added extra, however, was a spyware virus which invaded their home PCs and could steal personal data such as usernames and passwords.

A red-faced McDonald's has recalled the prizes and set up a help line advising consumers on how to get rid of the unwelcome visitor.

Comments IT security specialist Dennis Szerszen: "For free MP3 players, or any given technology for that matter, it's important to go through some measure of assurance that they cannot harm those that they are intended to amuse and entice."

Data sourced from Brand Republic (UK); additional content by WARC staff