Unique usernames 'allow spammers to track you'

Online criminals could launch a wave of highly targeted phishing attacks by matching usernames across the internet, researchers have found.

French security academics developed a system that cross-referenced publicly-available data from several major websites to build up detailed profiles of real people. The team harvested almost 10 million usernames from Google, eBay and MySpace.

Using statistical analysis techniques they showed that it is possible, to a high degree of certainty, to track about half of internet users across the internet based on only their username. They also showed that the more unique - the more entropy it has - the username, the more likely it is that it can be linked to a real person.