Inside the Rise of NETXLOADER and Qilin Ransomware: A New Era of Stealthy Cyberattacks

3 min readMay 8, 2025

A silent revolution is unfolding in the world of cyber threats. In a campaign traced back to November 2024, threat actors linked to the Qilin ransomware family introduced a stealthy new tool, a .NET-based loader dubbed NETXLOADER. Together with SmokeLoader, a known malware strain, this campaign signals a strategic and technical escalation in the ransomware landscape.

What makes this development significant is not just the malware itself, but how it’s being delivered. NETXLOADER is designed to evade traditional detection mechanisms, hidden behind heavy obfuscation and protected with .NET Reactor version 6. It’s no longer enough to scan strings or signatures-this loader requires real-time memory analysis to decode its behavior.

How the Attack Unfolds

The infection chain typically begins with phishing or compromised credentials. Once inside a network, NETXLOADER is dropped and proceeds to fetch additional payloads like SmokeLoader and Agenda ransomware from external command-and-control servers.

SmokeLoader initiates the second stage by performing advanced evasion techniques such as virtualization detection, sandbox escape, and process termination. The final blow is delivered via reflective DLL injection, where Agenda ransomware is launched to lock down files, infrastructure, and virtual systems such as ESXi environments.

What sets Agenda apart is its versatility. Its targets range across mounted drives, VCenter environments, and enterprise networks causing maximum disruption while exfiltrating sensitive data for extortion.

Why This Campaign Matters

Data from the first quarter of 2025 shows that Qilin has rapidly risen in the ranks, with over 45 victim disclosures in early April alone, overtaking ransomware groups like Akira and Lynx. The shutdown of RansomHub formerly a dominant ransomware player, has only funneled more affiliates into Qilin’s expanding operation.

Trend Micro’s analysis places the brunt of this campaign on industries such as:

Healthcare
Technology
Financial Services
Telecommunications

Each of these sectors handles mission-critical data and infrastructure, making them lucrative and damaging targets for ransomware actors.

Conclusion

The evolution of Qilin ransomware, powered by advanced loaders like NETXLOADER and delivery mechanisms like SmokeLoader, is a wake-up call. This isn’t just about locking files anymore. It’s about full-scale, multi-phase operations that evade traditional security tools and leverage legitimate network access for maximum impact.

To defend against such threats, organizations must embrace proactive cyber defense strategies, including advanced threat detection, secure development practices, and zero-trust architectures.

About COE Security

COE Security partners with organizations in financial services, healthcare, retail, manufacturing, and government to secure AI-powered systems and ensure compliance. Our offerings include:

AI-enhanced threat detection and real-time monitoring
Data governance aligned with GDPR, HIPAA, and PCI DSS
Secure model validation to guard against adversarial attacks
Customized training to embed AI security best practices
Penetration Testing (Mobile, Web, AI, Product, IoT, Network & Cloud)
Secure Software Development Consulting (SSDLC)
Customized CyberSecurity Services

In light of the threats posed by advanced loaders and ransomware campaigns like those involving NETXLOADER and Qilin, COE Security helps organizations in high-risk sectors build resilience through: