Cybersecurity professionals have uncovered a novel threat named QuirkyLoader-a sophisticated multi-stage malware loader deployed via spam emails that has been active since November 2024.
Key Threat Mechanics
- Spam emails carry an archive containing three elements: a legitimate executable, an encrypted payload disguised as a DLL, and a malicious DLL loader.
- The benign executable triggers the DLL loader via side-loading, which then decrypts and injects the final payload into trusted processes through process hollowing.
- QuirkyLoader stands out by using Ahead-of-Time (AOT) compilation for its .NET loader, enabling the final binary to appear like native C/C++-making detection significantly harder.
- Campaigns observed in July 2025 targeted Taiwan-specifically Nusoft Taiwan employees-with Snake Keylogger, and a broader campaign across Mexico delivering Remcos RAT and AsyncRAT.
Why It Matters to Your Organization
Industries such as financial services, healthcare, retail, manufacturing, and government remain prime targets for advanced malware campaigns like this. These sectors are particularly susceptible due to their reliance on file and email systems, where malware loaders like QuirkyLoader can open the door to data theft, unauthorized access, and persistent compromise.
How COE Security Supports Your Defense
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
Building on this, we provide:
- Simulated emulation of AOT malware loaders to test detection efficacy
- Email security posture assessments to block malicious archives and side-loading threats
- Real-time monitoring and alerting for abnormal behavior in processes like AddInProcess32.exe, InstallUtil.exe, and aspnet_wp.exe
- Training modules to educate teams on handling deceptive email attachments and recognizing suspicious delivery patterns
Conclusion
QuirkyLoader represents a stealthy evolution in loader malware, combining covert email delivery, side-loading, process injection, and advanced compilation techniques to evade detection. Organizations must respond with targeted detection strategies, secure architecture, and continuous awareness training to stay resilient.