NSA And FBI Warn Of Russian Linux Malware

The FBI and NSA have issued a joint report warning that Russian state hackers are using a previously unknown piece of Linux malware to stealthily infiltrate sensitive networks, steal confidential information and execute malicious commands. 

In the report, which is unusual for the depth of technical detail from a government agency, officials said the Drovorub malware is a full-featured tool kit that has gone undetected until recently. 

The malware connects to command and control servers operated by a hacking group that works for the GRU, Russia’s military intelligence agency that has been tied to more than a decade of brazen and advanced campaigns, many of which have inflicted serious damage to national security.

The US government agencies say that Drovorub, targets Linux systems. It says that the malware was developed for a Russian military unit enabling it to cyber-espionage hacks and attacks. The malware comes with a multitude of espionage capabilities, including stealing files and remotely controlling victims’ computers.

The malware is sophisticated and is designed for stealth, leveraging advanced “rootkit” technologies that make detection difficult. 

According to the National Security Agency (NSA) and the Federal Bureau of Investigation (FBI), the malware represents a threat to national security systems that use Linux. “Drovorub is a Linux malware toolkit consisting of an implant coupled with a kernel module rootkit, a file transfer and port forwarding tool, and a Command and Control (C2) server,” according to the joint report by the FBI and NSA.  “When deployed on a victim machine, the Drovorub implant (client) provides the capability for direct communications with actor controlled C2 infrastructure; file download and upload capabilities; execution of arbitrary commands as ‘root’; and port forwarding of network traffic to other hosts on the network.”

The report does not detail how the initial attack vector for the malware occurs. The report also does not specify how long the malware has been in action, or how many companies may have been targeted, and whether any attacks have been successful. Neither does it specify that the malware initially infects victims either.

It does say the threat actor behind the malware uses a “wide variety of proprietary and publicly known techniques to target networks and to persist their malware on commercial devices.”

The name “Drovorub” is derived from a variety of artifacts discovered in Drovorub files, used by the threat actors themselves, and translated, means “woodcutter” or “to split wood.” Drovorub, refers to a malware suite of four separate components that include an agent, client, server and kernel module. When deployed on a victim’s machine, the Drovorub client is first installed, and then provides the capability for direct communications with an actor-controlled command-and-control (C2) infrastructure.

When deployed on a victim machine, Drovorub provides the capability for direct communications with actor-controlled C2 infrastructure; file download and upload capabilities; execution of arbitrary commands; port forwarding of network traffic to other hosts on the network; and implements hiding techniques to evade detection. 

Once a client is in contact with the attacker controlled server, it then uses an agent component to receive commands. Those commands can trigger file download and upload capabilities, execution of arbitrary commands such as “root,” and port forwarding of network traffic to other hosts on the network.

The US government alleges the malware has been used in unspecified cyber-espionage operations that it has tied to the Russian General Staff Main Intelligence Directorate (GRU) 85th Main Special Service Center (GTsSS).

The report also cites what it believes are links between the malware and the Russian threat group Fancy Bear. This conclusion, the report states, came after linking operational Drovorub C2’s infrastructure with what it said was GTsSS operational cyber infrastructure.

Security researchers say that the malware’s functions can allow attackers to launch cyber warfare campaigns to disrupt companies, all without geographic proximity to the victim. NSA and FBI use a variety of sources, methods, and partnerships to acquire information about foreign cyber threats. 

FBI:      Threatpost:      NSA:     McAfee: 

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