Beware! Cellphone viruses at large!

Hi-tech viruses and malicious software programmes -- or malware -- commonly infect computers the world over: filling mail boxes with spam, deleting e-mail addresses, damaging machines and costing billions to corporations.

Now it might be the turn of your mobile phone to come under virus attack.

Junk messages might soon start flooding your cellphone even as a stealthy code sneaks into your handset using Bluetooth wireless technology!

A new Trojan horse aimed at smart phones which use Symbian operating system is on the loose and is attacking smartphones, but analysts say that the threat is still at a low level.

• World's first mobile phone virus found

The malware, MetalGear.a, which disguises as a Symbian version of the Metal Gear Solid game, can disable anti-virus programmes and can install a version of the Cabir worm that has infected mobile phones the world over, including India.

The Cabir worm, in turn, attempts to spread a second Trojan program, called SEXXXY, to nearby phones through the Bluetooth short-range wireless protocol.

A Trojan is malware that performs unexpected or unauthorized, often malicious, actions. The main difference between a Trojan and a virus is the inability to replicate. Trojans cause damage, unexpected system behavior, and compromise the security of systems, but do not replicate. If it replicates, then it should be classified as a virus.

A Trojan, coined from Greek mythology's Trojan horse, typically comes in good packaging but has some hidden malicious intent within its code. When a Trojan is executed users will likely experience unwanted system s, problems in operation, and sometimes loss of valuable data.

Some phones get infected when users open and install the fake Metal Gear game. Similar to the Skulls Trojan that has been at large since Novemberm, the MetalGear Trojan uses the same icon-disabling technique to disable anti-virus and other applications. The phones then cannot even be repaired as the malware disables all tools on the phone necessary to undo the damage.

The Skulls Trojan masquerades as a useful software but renders applications unlaunchable by replacing their icons, was also spotted on Nokia smartphones.

Many anti-virus specialists have introduced mobile anti-virus software to help counter this threat.