There's a stealthy Trojan, named Bankpatch.com, that is circulating in Denmark. Unlike most Trojans, which aim to grab information from wherever they can, this one is targeting specific banks.According to this Malicious Code Symantec blog post, this Trojan first surfaced in 2007, and the most recent .C version arriving in August of last year. The malware is targeting only certain banks:


However, the life of the threat continues today as the authors continue to distribute the threat and update plug-in modules that target specific banks. Most recently they've seen some success in Denmark deploying modules specifically focused on obtaining online banking credentials for numerous Danish banks. While Symantec is continuing deeper analysis of the threat's latest actions and modules, we wanted to provide a high-level overview of the threat.

Here's how Eric Chien describes how Bankpatch works:

Usually Bankpatch will arrive via a popular means of infection such as Web pages hosting exploits against Internet Explorer and third-party browser plug-in vulnerabilities. Once executed on the machine, Bankpatch will add code to multiple Windows system files and patch key routines so that when these routines are executed, execution is redirected to the injected code.



Bankpatch not only injects its code into these system files to hide itself but also uses them as a trigger mechanism to perform additional actions. For example, Bankpatch adds code and patches wininet.dll, which provides client network functionality. This allows Bankpatch to track when Internet Explorer is being used.



When a user begins a browsing session, Bankpatch will contact one of its command-and-control servers. Bankpatch first sends system information and then receives instructions. Currently, many of these command-and-control servers appear to be down.



Typically, additional DLLs are downloaded, including BHOs (Browser Helper Objects), which are loaded into Internet Explorer. These BHOs are customized to target certain online banking systems and proceed to steal users' online banking information. These BHOs will be detected as Infostealer.Nadebanker.

These types of targeted attacks can be much more difficult to spot. Couple that with the fact that they can be clandestinely inserted onto the systems of Web surfers doing nothing more than visiting what they believe to be "safe" sites makes the situation only worse.

We covered Trojan attacks targeting specific organizations, such as the South Korean military and similar attacks hitting U.K. government agencies and companies.