Advanced Malware Loaders: Leveraging Call Stack Spoofing, GitHub C2, and .NET Reactor for Enhanced Stealth

TL;DR

Cybersecurity researchers have uncovered an updated version of the Hijack Loader malware, which employs advanced techniques such as call stack spoofing, GitHub C2, and .NET Reactor to evade detection and establish persistence. This article explores these new features and their implications for cybersecurity.

Introduction

Cybersecurity researchers have identified a new variant of the Hijack Loader malware. This updated version incorporates sophisticated techniques to avoid detection and maintain a persistent presence on compromised systems. The malware employs call stack spoofing, GitHub C2, and .NET Reactor to enhance its stealth capabilities, making it a significant threat to cybersecurity defenses.

Call Stack Spoofing

One of the key features of the updated Hijack Loader is its implementation of call stack spoofing. This technique manipulates the call stack to conceal the origin of function calls, including API and system calls. By doing so, the malware can evade detection mechanisms that rely on tracking the source of these calls.

“Hijack Loader released a new module that implements call stack spoofing to hide the origin of function calls (e.g., API and system calls),” stated Muhammed Irfan V A, a researcher at Zscaler ThreatLabz¹.

GitHub C2 and .NET Reactor

In addition to call stack spoofing, the new Hijack Loader variant utilizes GitHub as a command and control (C2) server. This approach allows the malware to receive instructions and updates from a legitimate platform, further complicating detection efforts. Moreover, the malware employs .NET Reactor to obfuscate its code, making reverse engineering and analysis more challenging.

Implications for Cybersecurity

The advanced techniques employed by the updated Hijack Loader highlight the evolving nature of malware threats. Cybersecurity professionals must stay vigilant and adapt their detection and mitigation strategies to counter these sophisticated methods. Organizations should prioritize regular updates and comprehensive security audits to protect against such threats.

Conclusion

The new Hijack Loader variant represents a significant advancement in malware stealth techniques. By leveraging call stack spoofing, GitHub C2, and .NET Reactor, this malware poses a substantial risk to cybersecurity defenses. Staying informed about these developments and implementing robust security measures is crucial for safeguarding against such threats.

Additional Resources

For further insights, check:

• The Hacker News

References

1. Muhammed Irfan V A (2025). “New Malware Loaders Use Call Stack Spoofing, GitHub C2, and .NET Reactor for Stealth”. Zscaler ThreatLabz. Retrieved 2025-04-02. ↩︎