A newly discovered Trojan is intercepting the TAN codes used as security tokens by customers of two major German banks, Postbank and Deutsche Bank, according to anti-virus experts.
Until now, TAN codes were pretty safe, in particular against phishing attacks, as these tokens are sent either through (snail) mail or by SMS. Phishing scammers would not only have to know a customer's login details and password to enter an online bank account, but also the token to enable transactions. For this reason, many European banks have adopted the system for online banking.
Trojan-Spy.Win32.Bancos.pw is changing the security landscape once again, as it is able to intercept HTTPS traffic and obtain the security token pass code. When the customer tries to enter a TAN code, an error message appears. Phishing scammers, if they are quick enough, can then enter the code themselves.
The Trojan isn't widespread yet, nor have there been any reports of victims, "but there is no doubt we are going to see more of this", an expert warns. "It could render the use of tokens useless." ®