The Zeus malware specifically targeting the BlackBerry OS is currently detected by Trend Micro as BBOS_ZITMO.B. Once installed, the Trojan removes itself from the list of applications, in order to effectively stay under the radar.

Patrick Estavillo, threats analyst at Trend Micro says: "Banking trojans are evolving and more sophisticated attacks involving smartphones are among the most recent developments."

Zeus variants targeting smartphones running Symbian and Windows Mobile have previously been spotted in the wild, he notes

The Blackberry trojan allows a remote attacker to change the number to which it forwards SMS messages, block calls, remove blocks on other calls, add a new administrator and turn the phone on and off.

"With the increased popularity of mobile banking goes the increase of mobile threats," says Estavillo. "Thus users are strongly advised to keep their mobile devices secure, and be cautious in installing applications and clicking links sent by unknown users, as they may lead to the download of malicious applications."