The Storm Worm keeps on ticking. According to MessageLabs, the worm cranked out more than 15 million automated spam emails encouraging people to invest in penny stocks. In its current iteration, Storm is delivering the message via MP3 attached to the email.

UCSD researchers say that the infection rate of Storm has slowed, as has the total number of infected computers. In the last year, Storm has infected 15 million PCs, only about 160,000 of which are currently infected. ExitOnly, the company whose stock is the purchase target said it is not involved in the pump-and-dump scheme. Since the latest spam avalanche began, the company's stock price dropped by more than half, from $0.41 per share to $0.20.