The Turla campaign, also known as Snake or Uroburos, was originally uncovered in February, but goes back several years. The massive operation has infected computers at government organizations, embassies, military installations, education and research institutions and pharmaceutical companies in over 45 countries.
The newly identified Turla component for Linux was uploaded recently to a multi-engine antivirus scanning service and was described by security researchers from antivirus vendor Kaspersky Lab as "a previously unknown piece of a larger puzzle."
"So far, every single Turla sample we've encountered was designed for the Microsoft Windows family, 32 and 64 bit operating systems," the Kaspersky researchers said Monday in a blog post. "The newly discovered Turla sample is unusual in the fact that it's the first Turla sample targeting the Linux operating system that we have discovered."
The Turla Linux malware is based on an open-source backdoor program called cd00r developed in 2000. It allows attackers to execute arbitrary commands on a compromised system, but doesn't require elevated privileges or root access to function and listens to commands received via hidden TCP/UDP packets, making it stealthy.
"It can't be discovered via netstat, a commonly used administrative tool," said the Kaspersky researchers, who are still analyzing the malware's functionality.
"We suspect that this component was running for years at a victim site, but do not have concrete data to support that statement just yet," they said.
Since their blog post Monday, the Kaspersky researchers also found a second Turla Linux component that appears to be a separate malware program.