Anti-virus vendor Kaspersky Lab is reporting a new Trojan capable of removing pre-paid credit using the SMS-transfer service offered by an Indonesian network operator.
The Trojan is comprised of a Python script that sends SMS messages transferring small amounts, between 45 and 90 cents, to the attacker's account - presumably revealing the identity of the attacker or at least their beneficiary, though Kaspersky is light on those details.
The anti-virus vendor is, however, very clear on the best way to avoid infection - use their anti-virus software and ensure that it's kept up to date.
Alternatively you could just refuse to install unknown applications, and given that Symbian handsets ask for verification before sending an SMS you could refuse that too - but if you are afflicted by a condition that makes you agree to everything your phone asks, then you might want to consider some anti-virus software for your mobile phone. ®