Users of the popular AOL Instant messenger service are being targetted by a company using a stealthy 'adware' program which appears to be a simple game where players try to catch terrorist leader Osama Bin Laden.

The game, entitled Osama Found, is a front for a marketing 'virus' which, after installation, takes email addresses from the users AOL IM address book and automatically sends out messages, telling each contact to visit the game website.

The company responsible for the software, PSD Tools LLC of Cambridge, Massachusetts, is probably in violation of AOL's terms of service, since the instant messenger cannot be used to send unsolicited bulk communications or allow others to do it.