BRATISLAVA – ESET researchers have discovered a previously unknown malware family that utilizes custom and well-designed modules, targeting operating systems running Linux. Modules used by this malware family, which ESET dubbed FontOnLake, are constantly under development and provide remote access to the operators, collect credentials, and serve as a proxy server. The location of the C&C server and the countries from which the samples were uploaded to VirusTotal might indicate that its targets include Southeast Asia.
“The sneaky nature of FontOnLake’s tools in combination with advanced design and low prevalence suggest that they are used in targeted attacks,” explains Vladislav Hrčka, ESET Malware Researcher who analyzed this threat. To collect data or conduct other malicious activity, this malware family uses modified legitimate binaries that are adjusted to load further components. In fact, to conceal its existence, FontOnLake’s presence is always accompanied by a rootkit. These binaries are commonly used on Linux systems and can additionally serve as a persistence mechanism.
ESET researchers believe that FontOnLake’s operators are overly cautious since almost all samples seen by ESET use different, unique C&C servers with varying non-standard ports. The authors use mostly C/C++ and various third-party libraries such as Boost, Poco and Protobuf.
The first known file of this malware family appeared on VirusTotal last May and other samples were uploaded throughout the year. None of the C&C servers used in samples uploaded to VirusTotal were active at the time of writing, indicating that they could have been disabled due to the upload.
All known components of FontOnLake are detected by ESET products as Linux/FontOnLake. “Companies or individuals who want to protect their Linux endpoints or servers from this threat should use a multilayered security product and an updated version of their Linux distribution; some of the samples we have analyzed were created specifically for CentOS and Debian,” advises Hrčka.
Following ESET Research’s discovery while finalizing the FontOnLake white paper, vendors such as Tencent Security Response Center, Avast and Lacework Labs published their research on what appears to be the same malware. ESET will present its findings on FontOnLake on the AVAR 2021 Virtual conference held at the beginning of December.
For more technical details about FontOnLake, read the blogpost “FontOnLake: Previously unknown malware family targeting Linux” on WeLiveSecurity. Additional technical details can be found in our comprehensive white paper. Make sure to follow ESET Research on Twitter for the latest news from ESET Research.
About Version 2 Limited
Version 2 Limited is one of the most dynamic IT companies in Asia. The company develops and distributes IT products for Internet and IP-based networks, including communication systems, Internet software, security, network, and media products. Through an extensive network of channels, point of sales, resellers, and partnership companies, Version 2 Limited offers quality products and services which are highly acclaimed in the market. Its customers cover a wide spectrum which include Global 1000 enterprises, regional listed companies, public utilities, Government, a vast number of successful SMEs, and consumers in various Asian cities.
For 30 years, ESET® has been developing industry-leading IT security software and services for businesses and consumers worldwide. With solutions ranging from endpoint security to encryption and two-factor authentication, ESET’s high-performing, easy-to-use products give individuals and businesses the peace of mind to enjoy the full potential of their technology. ESET unobtrusively protects and monitors 24/7, updating defenses in real time to keep users safe and businesses running without interruption. Evolving threats require an evolving IT security company. Backed by R&D facilities worldwide, ESET became the first IT security company to earn 100 Virus Bulletin VB100 awards, identifying every single “in-the-wild” malware without interruption since 2003.