Greenshot.exe

Ransomware Operators Linked to The Gentlemen Deploy TukTuk C2 Framework for Espionage and Credential Theft

Operators associated with the ransomware group The Gentlemen have adopted a new command-and-control framework called TukTuk to steal credentials, monitor compromised systems, and prepare environments for ransomware deployment. The framework was discovered on a server that also hosted tools for disabling EDR solutions, research on vulnerable drivers, and data apparently stolen from two large organizations. TukTuk includes agents for both Windows and Linux, along with its own backend and management panel that allows remote command execution, file transfers, screen capture, and device tracking through a single interface. One notable feature displays a fake Windows Security window on the victim's machine to capture entered credentials and send them directly to the attackers' panel. Researchers identified a DLL sideloading technique that abuses the legitimate Greenshot.exe executable to load a malicious log4net.dll library and launch the TukTuk agent. The server also contained EDRKiller, WarsawKiller, and UnknownKiller tools, plus materials on BYOVD attacks that leverage vulnerable legitimate drivers to gain kernel access and interfere with security products.