A European bank may have lost as much as €500,000 (US$682,000) in a week earlier this year, according to Kaspersky Lab, which analyzed data on a server used in attacks against online banking users in Italy and Turkey.
In a blog post Wednesday, the Russian security company didn't identify the bank or why it chose to reveal the possible theft six months later. The financial institution has been notified of the discovery, and Kaspersky said is in contact with law enforcement.
On Jan. 20, Kaspersky analysts discovered a command-and-control server for a piece of malware that executed so-called man-in-the-browser attacks on victims' computers. In that type of attack, malware intervenes during an online banking session and can manipulate or steal data.
Two days later, the fraudsters removed all of the "sensitive components" from the server, Kaspersky wrote. That indicates the cybercriminals may have known someone else was looking at it.
The fraud campaign was nicknamed "Luuuk" by Kaspersky after that name appeared in a file path of the server's administrator control panel. It appears the server managed the theft of funds from victims' accounts, automatically transferring the money to the accounts of "mules," or people who agree to receive the funds for a cut and transfer the bulk of the funds onward.
Server logs indicated that as much as €500,000 may have been transferred in a single week, wrote Kaspersky's Global Research and Analysis Team. The data indicated around 190 victims. Analysts also saw on the server descriptions of fraudulent transfers and the IBAN (international bank account number) numbers for victims and money mules.
Kaspersky hasn't seen a sample of the actual malware that was on victims' computers. But data on the server indicated it is similar in functionality to the infamous Zeus banking malware.
The Luuuk malware collected the logins and passwords of victims and one-time passcodes. Since one-time passcodes typically expire in a few minutes, this type of banking malware will use the code to quickly log into the victim's account.
The attackers checked the victim's balance and then conducted several fraudulent transactions automatically, likely "in the background of a legitimate banking session," the company wrote.
There are other indicators that the group is still very active, Kaspersky wrote, although it did not give further details.
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