A newly discovered piece of malware combines ransomware and botnet capabilities in a single package, Trend Micro security researchers reveal.
Dubbed Virobot, the threat not only encrypts files on infected machines, but it also ensnares the system into a spam botnet and leverages it to spread itself to other victims.
First discovered on September 17, 2018, Virobot checks compromised machines for the presence of specific registry keys to determine if the system should be encrypted.
The ransomware uses a cryptographic Random Number Generator to generate the encryption and decryption key, which is then sent along with machine-gathered data to the command and control (C&C) server via POST.
For encryption, the malware targets file types such as .txt, .docx, .xlsx, .pptx, .jpg, .png, .csv, .sql, .mdb, .php, .asp, .xml, .psd, .odt, and .html, among others.
Once the encryption process has been completed, the malware displays a ransom note and a ransom screen. The ransom note is written in French, but the malware is currently affecting users in the United States, Trend Micro .
The malware’s server has been taken down, meaning that it can no longer encrypt files, as it requires communication with the C&C to do so.
Virobot, the security researchers discovered, also includes a keylogging feature. Logged key strokes from the infected machine are then sent to the C&C. Once connected to the server, the malware may also download files such as malware binaries, and execute them using PowerShell.
The botnet capabilities Virobot has been packed with include the use of an infected machine’s Microsoft Outlook to send spam emails to the user’s contact list. The malware sends either a copy of itself or a malicious payload downloaded from the C&C server.
“Individuals and enterprises should use a multi-layered approach to mitigate the risks brought by threats like ransomware,” Trend Micro said.