So far the Trojan Horse has simply collected passwords for online games, but experts say the designers might have larger targets in mind, the Seattle Post-Intelligencer reported Monday.

"It is a nasty worm that has a great deal of intelligence," said Brian Grayek, who heads product development at Computer Associates, a security vendor that analyzed the Trojan Horse.

The virus, which has been named Mocmex, blocks ant-ivirus protection from more than 100 vendors, as well as the security and firewall built into Microsoft Windows. It spreads by hiding itself on photo frames and other portable storage devices that are plugged into an infected PC.

The malware has "specific designs to capture something and not leave traces," Grayek said. "This would be a nuclear bomb" of malware.

He added that the Trojan has been traced to a specific group in China, but would not name the group.