Leak of ZeusVM malware building tool might cause botnet surge

The source code for the builder and control panel of ZeusVM version 2.0.0.0 was leaked sometime in June, according to a malware research outfit called Malware Must Die (MMD). The leak was kept under wraps by the researchers as they tried to stop the files from becoming widely available, an effort that ultimately exceeded their resources.

As a result, the group decided to go public with the information Sunday in order to alert the whole security community so that mitigation strategies can be developed.

ZeusVM, also known as KINS, is a computer Trojan that hijacks the browser process in order to modify or steal information from websites opened by victims on their computers. It's primarily used to steal online banking credentials, but other types of websites can also be targeted as long as attackers list them in the configuration file downloaded by the Trojan from the Internet.

As its name suggests, ZeusVM is based on the infamous Zeus Trojan, whose own source code was leaked in 2011 after years of being the primary malware tool used for online banking fraud.

It seems that the new ZeusVM leak does not contain the source code for the actual Trojan that could allow other malware writers to create more powerful variants. However, the builder and control panel is all that attackers need to start their own ZeusVM version 2 botnet, for free.

The builder is a program that allows attackers to create customized ZeusVM binary files, which can then be used to infect computers. The customization involves modifying things like the URL of the command-and-control server where the Trojan will connect or the key used to encrypt its configuration files.

The control panel is the Web application that runs on the command-and-control server and is used to receive and send data to ZeusVM-infected computers. It's needed to manage the botnet.

It's not clear who or why leaked the two ZeusVM tools, but the MMD researchers recently spotted sale offers for a new version of KINS -- version 3.0 -- on underground forums for US$5,000.

So in addition to a surge of new ZeusVM v2 botnets, the security community should also expect attacks with a new version of the Trojan soon, the MMD researchers said in their report.