A new virus will drain your bank account and then covers its own tracks by removing the unauthorized transactions and readjusting the balance, leaving the account holder with no way to know someone has hacked into the account.

The Trojan horse employs a powerful two-step process to commit the electronic crime. First, the virus lies in wait until a customer with an infected computer visits an online banking site, steals their login credentials and tricks the victim into divulging additional personal information such as debit card information. Then, after the stolen card number is used for a fraudulent purchase, the virus intercepts any further visits to the victim's banking site and scrubs transaction records clean of any fraud. That prevents -- or at least delays -- consumers from discovering fraud and reporting it to the bank, buying the fraudster critical extra time to complete the crime.

Trusteer calls it a "post transaction" attack, because much of the virus' effectiveness is attributable to its ability to control what victims see after fraudulent transactions occur. Amit Klein, chief technology officer for Trusteer, said he believes criminals have used the technique for a few months, and it has infected real consumers.