A cyber scam has stolen at least €500,000 from customers of a "large European bank" has been uncovered by Kaspersky Lab researchers.
Kaspersky Lab said it first uncovered evidence of the campaign, codenamed Luuuck, on 20 January, when experts detected a suspicious command and control (C&C) server on the internet.
The researchers detected transaction logs that chronicled how much the hackers have been stealing from each of their 190 victims. The amounts range from €1,700 to €39,000 per victim, earning the hackers an average of €500,000 per week.
Kaspersky Lab principal security researcher Vicente Diaz said it is currently unclear what type of malware is used to steal the money, though the firm suspects it is a modified version of Zeus, which automatically steals victims' financial information when they log in to their online bank account.
"On the C&C server we detected there was no information as to which specific malware program was used in this campaign. However, many existing Zeus variations (Citadel, SpyEye, Ice IX, etc) have that necessary capability. We believe the malware used in this campaign could be a Zeus flavour using sophisticated web injects on the victims," he said.
Kaspersky has contacted law enforcement and alerted the unnamed bank about the scam. Diaz said tracking the scammers is difficult as Luuuk uses an atypical method to send the stolen funds to them.
The scam reportedly involves a multitude of different groups spreading the money to various specially created bank accounts using "money mules". The different groups spreading the cash are reportedly responsible for handling differing amounts of money, and once in the accounts the cash is taken out of an ATM.
Diaz said the structured approach to transferring the money indicates that the scam is being run by an organised group. "These differences in the amount of money entrusted to different 'drops' may be indicative of varying levels of trust for each ‘drop' type. We know that members of these schemes often cheat their partners in crime and abscond with the money they were supposed to cash," he said
"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."
Cyber attacks targeting banking systems are an increasing problem facing governments and businesses. Law enforcement agencies across the world, including the UK National Crime Agency, attempted to mitigate the threat by mounting a co-ordinated takedown operation against the infamous Gameover Zeus botnet earlier this year.
Security experts told V3 earlier in June that, while the move was positive, law enforcement's more aggressive stance towards combating cyber crime could lead to a fresh wave of advanced cyber attacks.