About €500,000 has been stolen from accounts in an undisclosed large European bank in Italy and Turkey via a new banking Trojan campaign dubbed 'Luuuk', within a week during early 2014.
Security firm Kaspersky has identified more than 190 victims from whom the amount have been stolen with each bank account ranging between €1,700 and €39,000.
According to the security researchers, the campaign was detected after a Command and Control (C&C) server was discovered on the internet on 20 January.
Kaspersky Lab principal security researcher Vicente Diaz said: "Soon after we detected this C&C server, we contacted the bank's security service and the law enforcement agencies, and submitted all our evidence to them."
"On the C&C server we detected there was no information as to which specific malware program was used in this campaign," Diaz added.
"However, many existing Zeus variations (Citadel, SpyEye, IceIX, etc.) - have that necessary capability.
"We believe the malware used in this campaign could be a Zeus flavor using sophisticated web injects on the victims."
As part of the campaign, the malware also gathered the users' logins and passwords and one-time passcodes and also verified balance in the account and executed several fake transactions automatically.
Further, Kaspersky also found facts of several different 'drop' groups, with each of them being assigned with different sums of money.
"These differences in the amount of money entrusted to different drops may be indicative of varying levels of trust for each 'drop' type," Diaz added
"We know that members of these schemes often cheat their partners in crime and abscond with the money they were supposed to cash.
"The Luuuk's bosses may be trying to hedge against these losses by setting up different groups with different levels of trust: the more money a 'drop' is asked to handle, the more he is trusted."
However, the C&C server linked to The Luuuk had been packed up soon after the commencement of investigation.