Peter Kruse, security researcher with CSIS Security Group, said that the ZIP file contains the complete source code for Carberp and that the code compiles and works just as described in the text files included in archive.
It apparently also includes the Carberp bootkit and source code for the Stone bootkit, the Citadel Trojan, and other older malware, and text files its creator's IM communications and login credentials for various FTP servers.
The Carberp Trojan is a complex piece of banking malware that is capable not only of stealing sensitive information, but also of modifying a computer's hard drive's master boot record (MBR) in order to avoid being detected by antivirus software present on the targeted machine.
Earlier this year, the mastermind behind Carberp and the developers that helped created it have apparently been arrested in Ukraine. Nevertheless, the source code for the malware was being sold on underground forums for as much as $50,000, which given the earning potential of the malware, was not at all surprising.
So why is it now being offered for free? There are many speculations, but among the most likely is that the source code has been modified to open a backdoor into the system to the original "seller".
Security researchers are predicting that a lot of malware developers will download, modify and use the code, leading to a slew of similar malware - a situation that will mirror that which happened when the Zeus source code was being sold at bargain basement prices and ultimately leaked.