The CamuBot Trojan is a new malware variant that is being used in vishing campaigns on employees to obtain banking credentials.

Cybercriminals Use Vishing to Convince Employees to Install CamuBot Trojan

Spam email may be the primary method of delivering banking Trojans, but there are other ways of convincing employees to download and run malware on their computers.

In the case of the CamuBot Trojan the method used is vishing. Vishing is the voice equivalent of phishing – The use of the telephone to scam people, either by convincing them to reveal sensitive information or to take some other action such as downloading malware or making fraudulent bank transfers.

Vishing is commonly used in tech support scams where people are convinced to install fake security software to remove fictitious viruses on their computers. The campaign used to install the CamuBot Trojan is a variation on this theme and was uncovered by IBM X-Force researchers.

The attack starts with some reconnaissance. The attackers identify a business that uses a specific bank. Individuals within that organization are then identified that are likely to have access the bank accounts used by the business – payroll staff for example. Those individuals are then contacted by telephone.

The attackers claim that they are calling from the bank and are performing a check of security software on the user’s computer. The user is instructed to visit a webpage where a program will run a scan to find out if they have an up-to-date security module installed on their computer.

The fake scan is completed, and the user is informed that their security module is out of date. The caller then explains that the user must download the latest version of the security module and install it on their computer.

Once the file is downloaded and executed, it runs just like any standard software installer. The user is advised of the minimum system requirements needed for the security module to work and the installer includes the bank’s logo and color scheme to make it appear genuine.

The user is guided through the installation process, which first requires them to stop certain processes that are running on their computer. The installer displays the progress of the fake installation, but in the background, the CamuBot Trojan is being installed. Once the process is completed, it connects to its C2 server.

The user is then directed to what appears to be the login portal for their bank where they are required to enter their login credentials. The portal is a phishing webpage, and the credentials to access the users bank account are captured by the attacker.

Many banks require a second factor for authentication. If such a control is in place, the attackers will instruct the user that a further installation is required for the security module to work. They will be talked through the installation of a driver that allows a hardware-based authentication device to be remotely shared with the attacker. Once that has been installed and approved, the attackers are able to intercept any one-time passwords that are sent by the bank to the user’s device, allowing the attackers to take full control of the bank account and authorize transactions.

The CamuBot Trojan shows that malware does not need to be stealthy to be successful. Social engineering techniques can be just a effective at getting employees to install malware.

The CambuBot Trojan campaign is primarily being conducted in Brazil, but the campaign could be rolled out and used in attacks in other countries. The techniques used in this campaign are not new and have ben used in several malware campaigns in the past.

Consequently, it is important for this type of attack to be covered as part of security awareness training programs. Use of a web filter will also help to prevent these attacks from succeeding by blocking access to the malicious pages where the malware is downloaded.