The Trojans were used in attacks in Poland, targeting customers of ING Bank, Polish security consultant and blogger Piotr Konieczny reported.
Both versions attempted to steal data from victims’ smartphones and resemble older variants of the malware.
Targets were asked to enter their mobile phone number and smartphone model for a purported ‘certificate update’.
A component was then installed on victims' smartphones, which intercepted text messages and relayed them to another mobile number.
Both Zeus variants reported back to a British command and control mobile phone number once they successfully infiltrated a device.
“If users would have downloaded and installed this malicious file, their incoming SMS messages (with mTAN authentication codes also) would have been resent silently to a predefined cell phone number,” explained Denis Maslennikov, a malware researcher at Kaspersky Lab.
He said the Trojans show how cyber criminals continue to target new platforms and remain determined in their attempts to acquire user data from an array of devices.
Benjamin Boulnois, manager of DigitalPersona for Europe, the Middle East and Africa (EMEA), said mobile devices need better security software to keep up with new threats.
“There's clearly an urgent need for stronger software on mobile devices that can not only recognise Trojans themselves, but can also prevent users from unwittingly accessing fraudulent bank websites, which is often how devices become infected,” Boulnois said.
“What's more, security software must be able to detect any anomalies in how accounts are being accessed - for example if someone is logging in from a different device or location, or at different times, compared to normal.”
Britain's Foreign Secretary William Hague recently revealed the UK Government had been targeted by a Zeus Trojan.