A Look Into CPL Malware
Last month, we published a blog post describing how Control Panel malware was being distributed via malicious attachments to Brazilian users. We have continued to look into these threats, and we have now released a research paper titled CPL Malware: Malicious Control Panel Items covering the the structural aspects of CPL files and how criminals are using it to spread malware mainly in Brazil.
Currently, this particular threat is being commonly used to spread banking malware in Brazil. Typically, these users are sent financial-themed mails that contain a link to a malicious compressed file. When the contents of this file are uncompressed, the user sees several the malicious .CPL file(s).
Figure 1. Typical CPL Malware Behavior
In terms of analysis, looking at a CPL file is essentially identical to a DLL file. However, unlike the latter, it is automatically run when double-clicked. This makes it similar to EXE files; however uneducated users may be more likely to try to execute CPL files if they do not know any better. Most CPL malware from Brazil were written in Delphi, which is a popular programming language in the country.
In Brazil, CPL files are used for banking malware almost as frequently as EXE files, with both file types combining for almost 90% of the banking malware seen in Brazil from March to November 2013. For the past two years (2012 and 2013), we have detected approximately a quarter million CPL malware in the country. It is currently a significant problem for Brazilian users and organizations.