Cyber criminals are targeting UK bank customers with a new technique that combines a new version of the Ramnit Trojan and social engineering techniques to bypass One Time Password Security in a sophisticated attack that diverts funds to a money “mule” who is duped into laundering the stolen funds in ‘real time’.

According to Etay Maor, Fraud Prevention Solutions Manager for Trusteer analyzed a Ramnit variant that is targeting a UK bank with a clever one-time password (OTP) scam. The malware stays idle until the user successfully logs into their account, at which time it presents them with warning messages. While the user is reading the message, Ramnit connects to its command and control server and obtains the details of a designated mule account. This is followed by the initiation of a wire transfer to the money mule. But, there is still one more obstacle in the way of the malware – to complete the transaction a One Time Password (OTP) must be entered by the user. To overcome this requirement Ramnit displays a message giving the user a temporary receiver number which is actually the mule’s account number.

The user then receives the SMS and thinking that he must complete the “OTP service generation”, enters their OTP. By entering the OTP, the user unknowingly enables the malware to complete the fraudulent transaction and finalise the payment to the mule account. This is yet another example of how well designed social engineering techniques help streamline the fraud process.

Ramnit’s creators built a fake version of the bank’s FAQ page to explain the new process so that users would think it was normal. Maor said that it is an example of the steps that modern bank robbers are taking to convince people to hand over their details.