The China-backed threat actor Earth Baku has diversified its targeting footprint beyond the Indo-Pacific region to include Europe, the Middle East, and Africa starting in late 2022. Newly targeted countries include Italy, Germany, the U.A.E., and Qatar, with suspected attacks also detected in Georgia and Romania. Governments, media and communications, telecoms, technology, healthcare, and education sectors are among those singled out as part of the intrusion set.

Trend Micro researchers Ted Lee and Theo Chen, in an analysis published last week, noted that Earth Baku has updated its tools, tactics, and procedures (TTPs) in more recent campaigns. The group utilizes public-facing applications such as IIS servers as entry points for attacks, subsequently deploying sophisticated malware toolsets on the victim's environment. The findings build upon recent reports from Zscaler and Google-owned Mandiant, which also detailed the threat actor's use of malware families like DodgeBox (aka DUSTPAN) and MoonWalk (aka DUSTTRAP). Trend Micro has assigned them the monikers StealthReacher and SneakCross.

Earth Baku, a threat actor associated with APT41, has been known for its use of StealthVector as far back as October 2020. Their attack chains involve the exploitation of public-facing applications to drop the Godzilla web shell, which is then used to deliver follow-on payloads. StealthReacher has been classified as an enhanced version of the StealthVector backdoor loader, responsible for launching SneakCross, a modular implant and a likely successor to ScrambleCross that leverages Google services for its command-and-control (C2) communication.

The attacks are further characterized by the use of other post-exploitation tools such as iox, Rakshasa, and a Virtual Private Network (VPN) service known as Tailscale. Sensitive data exfiltration to the MEGA cloud storage service is accomplished by means of a command-line utility dubbed MEGAcmd. "The group has employed new loaders such as StealthVector and StealthReacher to stealthily launch backdoor components, and added SneakCross as their latest modular backdoor," the researchers stated.

"The persistence of Earth Baku is notable," said the researchers. "Their tactics show a sophisticated understanding of public-facing applications, allowing them to infiltrate various sectors with precision." They further explained that the group's post-exploitation tools are customized to fit specific operational needs, with iox and Rakshasa playing significant roles in maintaining prolonged access and stealth. Tailscale, the VPN service, ensures the attackers can manage their operations without detection, while MEGAcmd allows for efficient data exfiltration.

The continued evolution of Earth Baku's methods, including the introduction of new malware like SneakCross, highlights the growing complexity and threat posed by this actor. The group’s ability to adapt and refine their TTPs makes them a formidable adversary in the cyber landscape.