Researchers at Russian antivirus firm Dr. Web have come across a couple of new Linux Trojans, including one that abuses Raspberry Pi computers for cryptocurrency mining.
The malware, tracked by the company as Linux.MulDrop.14, has been described as a script that contains a compressed and encrypted cryptocurrency miner.
The Trojan attempts to connect to a device via SSH using the default credentials – the username “pi” and the password “raspberry.” If the device is successfully infected, the miner is unpacked and executed. The Trojan then changes the device’s password and starts looking for other Raspberry Pi computers it can connect to via SSH over port 22.
MulDrop, which researchers first spotted in mid-May, uses the ZMap scanner to search for other victims, and the sshpass utility to connect to them. The process for attempting to infect other devices takes place in an infinite loop, Dr. Web said.
An update released in November 2016 for the Raspbian operating system disables the SSH server by default. Users who have SSH enabled on their Raspberry Pi have been advised to change their default password to prevent attacks.
Raspberry Pi devices have been targeted by malware in the past. Symantec reported last year that Internet of Things (IoT) malware that abused infected devices for distributed denial-of-service (DDoS) attacks had also targeted Raspberry Pis.
Another Linux Trojan discovered recently by Dr. Web is Linux.ProxyM, which has been around since February. The number of ProxyM attacks peaked in late May with roughly 10,000 attempts per day. Nearly one-third of the attacks were traced to Russia, and other offending IPs were linked to China (13%), Taiwan (10%) and Brazil (9%).
ProxyM has been used by malicious actors to cover their tracks online. Once it infects a Linux device, the Trojan uses various methods to detect honeypots. If a honeypot is not detected, the malware contacts a command and control (C&C) server and initiates a SOCKS proxy server on the compromised machine.