Microsoft researchers have recently discovered an attack leveraging custom and open-source tools to target internet-facing Linux-based systems and IoT devices. The attack uses a patched version of OpenSSH to take control of impacted devices and install cryptomining malware.

Utilizing an established criminal infrastructure that has incorporated the use of a Southeast Asian financial institution’s subdomain as a command and control (C2) server, the threat actors behind the attack use a backdoor that deploys a wide array of tools and components such as rootkits and an IRC bot to steal device resources for mining operations. The backdoor also installs a patched version of OpenSSH on affected devices, allowing threat actors to hijack SSH credentials, move laterally within the network, and conceal malicious SSH connections. The complexity and scope of this attack are indicative of the efforts attackers make to evade detection.