I see viruses as being on the cusp of a revolution. While it's true we've seen viruses move from computer to PDA in the past (I wish I could find a source, but at the moment I can't), this has so far failed to cause any major outbreaks. However, as the typical handheld device becomes increasingly complex and internetworked, the potential damage for such a worm has grown significantly in the past few years. This threat is especially pronounced with cellular devices. Recently, a virus was written that tried - unsuccessfully - to make the jump from a cellphone to PC. The spread method was rudimentary, using a smart card as the carrier mechanism for the code. But it foreshadows more virulent threats to come. Consider the different propogation vectors that are now available between some devices and "ordinary" computers that never used to exist:
- Conventional PDA's. Data is transferrable via (1) memory chip, as with the aforementioned virus, (2) bluetooth, and (3) USB connection. Targets could include other PDA's, or PC's. Most of these devices are also infrared-enabled, as well, but I'd consider this threat minimal due to limitations of the technology.
- Cellular Phones. Resembling more and more of a computer as the months progress, potential device-to-computer data paths include (1) memory chip, (2) SMS text messaging to other devices like blackberries, (3) instant messaging, and (4) bluetooth. And that's not beginning to cover the functionality available in devices like the Treo.
- Blackberry devices. These are the penultimate virus propogation devices. They communicate with other devices via (1) internet access on the cellular network, (2) bluetooth, (3) SMS to other portable devices, (4) Instant Messaging through a third-party app, (5) Email, and (6) USB connection. That's no less than SIX different vectors an infected Blackberry device could leverage to attack other devices like cell phones or ordinary computer systems.
- IP Phones. These don't represent a bridge between computers and mobile devices yet, but the phone on your desk is now a device that potentially touches the same data network as your computer, and the same phone network as your cell.