Next year will be a grim one for smartphone and PDA users.

Rising threat levels for mobile users should come as no surprise, but McAfee’s Avert Labs division has marked 2006 down as a potential turning point in the spread of malware to these platforms.

Keylogging Trojans, adware, bots and backdoor programs will all hit users with greater frequency in 2006, with smartphone and “converged” users witnessing damage much greater than that seen on PCs because few currently bother to protect themselves.

“Consumers are less likely to install mobile security versus PC security because the perceived risk from mobile threats is much less,” a company release said.

According to McAfee, mobile malware has grown ten times more rapidly than PC threats over any period of one year, and that in general “potentially unwanted programs” (PUPs) have grown by 40 percent in 2005 alone.

The problem appears to be the increasing usefulness of Smartphones and PDAs. Having spent years as technological curiosities, they are now being sold to perform a variety of useful but risky operations such as mobile banking.

The most plausible threat to mobile users remained that of fast-infecting viruses, however.

Sceptics will contend that McAfee is indulging in a spot of end-of-year scaremongering as a marketing aid for its own mobile anti-virus systems. The company’s Virusscan Mobile, for instance, is a $29.95 download for anyone who wants to protect a device running Microsoft Smartphone or Pocket PC.

There is little doubt that mobile threats will be on the rise in the next year, but it is hard to compare these levels with that faced by PC users. However attractive a target, the average mobile cannot be attacked for much profit, and there are also several platforms to contend with.

A more likely scenario is that there will be a series of nuisance attacks, building on the crude information hacking that has afflicted mobiles in the least year. In principle, the best defence against this is not to wait for users to buy a software defence, but to build it in as a standard feature from the outset.