Planted on Networks, Phony Download Infects 500K PCs

Almost 500,000 people have unintentionally downloaded an adware bundle from file-sharing networks in the past week, security firm McAfee says, with ugly consequences. Disguised as a music file or popular movies, the phony file is circulating on the eDonkey and Limewire networks. It asks users to install a codec to play the file, and then overwhelms them with popup ads, the BBC reports.

Only 10% of the users who downloaded the malicious file have actually installed the codec, McAfee says. Other security companies have seen the problem file, but not in such great numbers. McAfee said the large scale of the attack is unusual from cybercriminals, who usually like to stay lower-profile. Only Windows users are at risk from the trojan. (More malware stories.)