This post was originally published on Security Affairs. It can be found here.
Acronis researchers reported that new Chaos RAT variants were employed in 2025 attacks against Linux and Windows systems.
Acronis TRU researchers discovered new Chaos RAT variants targeting Linux and Windows in recent attacks. Originally seen in 2022, Chaos RAT evolved in 2024, with fresh samples emerging in 2025. TRU also discovered a critical flaw in the RAT’s web panel that enables remote code execution. The latest variant appears to trick victims into downloading a fake Linux network troubleshooting tool, further expanding its infection methods.
“Developed in Golang, Chaos RAT offers cross-platform compatibility with Windows and Linux systems — another clear example of how useful legitimate tools can contain vulnerabilities and be repurposed for cybercriminal activities.” reads the report published by Acronis. “While overall use remains limited, recent samples confirm Chaos RAT is still active. Its low detection profile creates opportunities for espionage, data exfiltration, and establishing footholds for ransomware and other post-compromise operations.”
Chaos RAT is an open-source remote access tool (RAT) built in Golang, designed to work across both Windows and Linux systems. The RAT is inspired by tools like Cobalt Strike and Sliver. It includes an admin panel where attackers can create payloads, manage sessions, and control infected devices. While Golang-based malware is typically larger and slower than C++ versions, it offers easier cross-platform support and faster development, making it appealing to cybercriminals.
Chaos RAT, initially built for legitimate remote management, has been repurposed by threat actors due to its open-source nature. Though development began in 2017, it was first employed in real-world attacks in late 2022, mainly targeting Linux systems in crypto-mining campaigns. Its growing use highlights the need to understand its architecture, attack methods, and how to detect and defend against it.
The RAT often spreads through phishing emails with malicious links or attachments. Early attacks used cron jobs to keep updating payloads remotely, allowing attackers to deploy crypto miners or Chaos RAT without re-accessing the system. The RAT was mainly used for reconnaissance. In a recent case from India, a file named NetworkAnalyzer.tar.gz contained the RAT, disguised as a Linux network tool, suggesting that attackers used social engineering to trick the victim.
Chaos RAT offers a range of commands for system control and data theft. It can gather OS and user info, take screenshots, reboot or shut down the system, lock or sign out users (Windows only), browse and manage files (explore, upload, download, delete), and open URLs in the default browser. It supports both Windows and Linux, with some OS-specific features. These capabilities allow operators to control infected systems and exfiltrate data remotely.
Chaos RAT enables attackers to manage files, open reverse shells, and proxy network traffic, which are functions useful for spying, stealing data, or setting the stage for ransomware. Because it’s open-source, threat actors can easily tweak the code to avoid detection, making it harder to trace attacks or distinguish between cybercriminals and nation-state groups using the same tool.
“What starts as a developer’s tool can quickly become a threat actor’s instrument of choice. This Go-based RAT offers a simple web interface and powerful system controls across Windows and Linux, offering reverse shells, file manipulation and remote command execution on compromised systems.” concludes the report. “Chaos has been spotted in the wild and represents a growing issue in cybersecurity: The weaponization of open-source software. With rapid deployment capabilities, stealthy Linux targeting and flexible configuration, it’s a reminder that open source is a double-edged sword — and in the wrong hands, it can cut deep.“
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Pierluigi Paganini
(SecurityAffairs – hacking, malware)
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