Protection software Viruses that target handhelds can be even more dangerous than their cousins that attack PCs, spawning self-replicating programs that hide easily, a security researcher told an audience of security professionals at the Black Hat Briefings conference here this week.

The first virus aimed at Pocket PC handhelds, revealed last week, could be far worse if it were modified slightly to carry a harmful payload, said Seth Fogie, a vice president of Airscanner, which develops security software for the Window Mobile platform.

The benign WinCE4.Duts.A (or just "Dust") virus was created as a demonstration of threats against personal digital assistants. However, Fogie noted, such programs could spread stealthily, logging keystrokes on the Pocket PC's "soft keyboard," and sending data stored on handhelds across the Internet.