Kaspersky researchers have identified the reemergence of the MysterySnail RAT, a malware previously linked to the Chinese IronHusky APT group. This new version of the RAT targets government entities in Mongolia and Russia, reflecting the group’s long-standing interest in these regions since 2018. The RAT’s modular design and advanced tactics indicate a strategic evolution from its previous incarnation, with improvements in its ability to execute multiple malicious actions.
The recent infection cycle began with a malicious MMC script disguised as a document from Mongolia’s National Land Agency.
This script downloaded a ZIP archive containing a secondary malicious component along with a decoy DOCX file. Upon extraction, the archive placed a decoy document in the system and executed a legitimate Cisco application, which facilitated the loading of the malicious CiscoSparkLauncher.dll, acting as a backdoor for communication with C2 servers.
The updated MysterySnail RAT can execute up to 40 different commands, enhancing its operational capabilities. These commands include file system manipulation, command execution, service management, and network access. Notably, the RAT now uses five DLL modules for command execution, which adds complexity and makes detection more difficult compared to the 2021 variant, which only used a single malicious component.
After the disruption of MysterySnail RAT’s activities, a modified version named MysteryMonoSnail was deployed.
This simplified variant communicates using the WebSocket protocol, reducing its functionality to only 13 commands, including directory listing and process execution. This incident illustrates how older malware can evolve and adapt, making it crucial for cybersecurity teams to stay vigilant and prepared for the resurgence of such threats.
