Owners of jailbroken iPhones are at risk from a newly discovered worm, a web security firm has warned.
According to F-Secure, the worm is affecting Dutch handset users who have been using their phone for online banking with ING Direct.
Unlike the recent largely harmless Ikee, rickrolling iPhone worm, the threat identified by F-Secure installs a backdoor on handsets and allows a botnet to take control.
This means that affected mobiles can be controlled remotely and accessed by hackers in search of bank details.
Mikko Hypponen, research director at F-Secure, told BBC Online: "It's the second iPhone worm ever and the first that's clearly malicious - there's a clear financial motive behind it.
"It's fairly isolated and specific to Netherlands but it is capable of spreading."
Only iPhones that have been jailbroken, that is those which have been modified to run non-Apple software, and which have file transfer program SSH installed are vulnerable to the worm.
It is thought that the number of handsets infected is currently in the hundreds.