ESET Research: Russia-aligned Turla group likely uses Lunar arsenal to target & spy on European diplomats

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ESET Research discovered two previously unknown backdoors — which we named LunarWeb and LunarMail — compromising a European ministry of foreign affairs and its diplomatic missions abroad, primarily in the Middle East. ESET believes that the Lunar toolset has been used since at least 2020 and, given the similarities between the tactics, techniques, and procedures and past activities, ESET researchers attribute these compromises with medium confidence to the infamous Russia-aligned cyberespionage group Turla. The aim of the campaign is cyberespionage.

The ESET investigation began with the detection of a loader deployed on an unidentified server, which decrypts and loads a payload from a file. This led ESET researchers to the discovery of a previously unknown backdoor, which ESET named LunarWeb. Subsequently, a similar chain with LunarWeb deployed at a diplomatic mission was detected. Notably, the attacker also included a second backdoor — which ESET named LunarMail — that uses a different method for command and control (C&C) communications. During another attack, ESET observed simultaneous deployments of a chain with LunarWeb at three diplomatic missions of a European country in the Middle East, occurring within minutes of each other. The attacker probably had prior access to the domain controller of the ministry of foreign affairs and utilised it for lateral movement to machines of related institutions in the same network.

LunarWeb, deployed on servers, uses HTTP(S) for its C&C communications and mimics legitimate requests, while LunarMail, deployed on workstations, persists as an Outlook add-in and uses email messages for its C&C communications. Both backdoors employ steganography, a technique in which commands are hidden in images to avoid detection. Their loaders can exist in various forms, including trojanised open-source software, demonstrating the advanced techniques used by the attackers.

“We observed varying degrees of sophistication in the compromises — for example, the careful installation on the compromised server to avoid scanning by security software contrasted with coding errors and different coding styles of the backdoors. This suggests multiple individuals were probably involved in the development and operation of these tools,” says ESET researcher Filip Jurčacko, who discovered the Lunar toolset.

Recovered installation-related components and attacker activity suggest that possible initial compromise happened via spearphishing and abuse of misconfigured network and application monitoring software Zabbix. Furthermore, the attacker already had network access, used stolen credentials for lateral movement, and took careful steps to compromise the server without raising suspicion. In another compromise, researchers found an older malicious Word document, likely from a spearphishing email.

LunarWeb collects and exfiltrates information from the system, such as computer and operating system information, a list of running processes, a list of services, and a list of installed security products.  LunarWeb supports common backdoor capabilities, including file and process operations, and running shell commands. On first run, the LunarMail backdoor collects information from recipients’ sent email messages (email addresses). In terms of command capabilities, LunarMail is simpler and features a subset of the commands found in LunarWeb. It can write a file, create a new process, take a screenshot, and modify the C&C communication email address. Both backdoors have the unusual capability of being able to execute Lua scripts.

Turla, also known as Snake, has been active since at least 2004, possibly even dating back to the late 1990s. Believed to be part of the Russian FSB, Turla mainly targets high-profile entities such as governments and diplomatic organisations in Europe, Central Asia, and the Middle East. The group is notorious for breaching major organisations, including the US Department of Defense in 2008 and the Swiss defense company RUAG in 2014.

For more technical information about the Lunar toolset, read the blogpost “To the Moon and back(doors): Lunar landing in diplomatic missions.” Make sure to follow ESET Research on Twitter (today known as X) for the latest news.

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