Ransomware Hackers Use New TukTuk Malware to Steal Credentials and Disable Security Tools

Ransomware operators are using a previously undocumented remote-control framework called TukTuk to steal credentials, watch compromised machines, and weaken protections.

The discovery links the tool to activity associated with the Gentlemen ransomware operation and shows how one intrusion can combine access theft, surveillance, and defense evasion.

Its recovery gives defenders an unusual view of the infrastructure and research that can sit behind a ransomware operation.

The framework was recovered from a server holding a malicious DLL sideloading set, EDR-disabling tools, and data believed taken from two large organizations.

That mix suggests a prepared attack environment, able to move from an initial foothold to data theft and ransomware deployment.

It also gives incident responders several distinct traces to investigate. That breadth complicates containment and raises the risk of repeat intrusion. Oasis Security analysts identified the complete TukTuk project, including Windows and Linux agents, a backend, and an operator panel.

Oasis Security said in a report shared with Cyber Security News (CSN) that the findings also included 224 Jira tickets and eight attachments assessed as exfiltrated from a global technology company, alongside cloud and infrastructure credentials tied to a healthcare organization.

The exposure potentially reaches beyond one victim. The Jira records reportedly included technical information connected with US defense and defense-industry customers, while the healthcare material covered AWS, Azure AD, Bitbucket, production databases, and configuration systems.

The group appears to be gathering information for later access, extortion, or follow-on attacks, increasing the potential cost of a single compromise.

Ransomware Hackers Use New TukTuk Malware

TukTuk is a command-and-control framework that lets an operator manage infected devices from a central panel.

Its Windows agent can collect system details, communicate with the server, run commands, handle files, and capture screens, while the separate Linux agent points to a cross-platform design, which is notable for organizations operating mixed server and workstation estates.

The panel also exposes an especially direct credential-theft option. An operator can trigger a fake Windows Security prompt that resembles the legitimate interface; information entered by the user is then recorded in TukTuk.

This turns a compromised endpoint into a password-collection tool, beyond technical exploits. The discovery follows reporting on GentleKiller ransomware defense evasion, which described the same ransomware ecosystem using vulnerable drivers to shut down endpoint protections.

TukTuk adds a wider control layer for tracking agents, commands, screenshots, and stolen credentials before encryption. Researchers also found a sideloading package using the legitimate Greenshot.exe program and malicious log4net.dll.

In this technique, a trusted application is made to load an attacker-controlled library from its own folder, a pattern also seen in recent DLL sideloading campaigns that hide malicious code behind normal-looking software.

Security Tools Were a Deliberate Target

The server contained training material arranged across four lessons on neutralizing EDR products and hunting for vulnerable drivers.

It included eb.sys, a driver whose hash matches a publicly documented GentleKiller sample, plus EDRKiller, WarsawKiller, and UnknownKiller materials. The documents suggest the actors studied how long protections take to recover after process termination.

A vulnerable driver can give attackers deep Windows control, enabling interference with security software before ransomware is launched.

Organizations can reduce that opportunity by enforcing driver allowlisting, enabling Microsoft’s Vulnerable Driver Blocklist, and investigating unexpected driver installations or kernel-level service creation.

Reporting on ransomware EDR killer tactics shows these methods are recurring ransomware tactics. Defenders should also watch for legitimate programs loading unusual nearby DLLs, unexpected credential prompts, and unexplained screen-capture or remote-command behavior.

Sideloading can make a malicious process look routine. The related Mistic credential theft campaign illustrates why endpoint teams should inspect suspicious DLL-to-process relationships rather than relying on file names alone.

Potentially exposed organizations should rotate credentials, review cloud logs, and check Jira-like platforms for secrets and unusually broad downloads.

Teams should block listed indicators, isolate suspected hosts, preserve evidence, and hunt across Windows and Linux environments.

The research group said relevant findings had been shared with affected organizations and institutions. Fast coordination between security, identity, and cloud teams is essential.

Indicators of compromise (IoCs):-

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