Unveiling PowerShell-Based Attacks: Fileless Remcos RAT Deployed via LNK Files and MSHTA

TL;DR

Cybersecurity researchers have uncovered a sophisticated malware campaign utilizing PowerShell-based shellcode loaders to deploy the Remcos RAT. This attack involves malicious LNK files embedded in ZIP archives, often disguised as Office documents, and leverages mshta.exe for execution. The campaign highlights the evolving tactics of threat actors and the importance of vigilant cybersecurity measures.

Introduction

Cybersecurity researchers have recently shed light on a sophisticated malware campaign that employs PowerShell-based shellcode loaders to deploy the Remcos Remote Access Trojan (RAT). This advanced threat utilizes a complex attack chain involving malicious LNK files embedded within ZIP archives, often disguised as innocuous Office documents. The campaign underscores the evolving tactics used by threat actors to bypass traditional security measures and highlights the critical need for robust cybersecurity defenses.

Attack Chain Overview

The attack begins with the delivery of malicious LNK files embedded within ZIP archives. These archives are cleverly disguised as legitimate Office documents to deceive unsuspecting victims into opening them. According to Qualys security researcher Akshay Thorve, the attack chain leverages mshta.exe to execute the malicious payload ¹.

Key Components of the Attack

1. Delivery Method: Malicious LNK files are embedded within ZIP archives, disguised as Office documents.
2. Execution: The attack chain leverages mshta.exe to execute the malicious payload.
3. Payload: A PowerShell-based shellcode loader deploys the Remcos RAT.

Impact and Implications

The Remcos RAT is a powerful tool that allows attackers to gain remote access and control over compromised systems. This can lead to data exfiltration, further malware deployment, and other malicious activities. The use of fileless techniques makes detection and mitigation more challenging, emphasizing the need for advanced endpoint protection and continuous monitoring.

Conclusion

The discovery of this PowerShell-based attack campaign deploying the Remcos RAT via LNK files and MSHTA highlights the ongoing evolution of cyber threats. Organizations must remain vigilant and implement comprehensive security measures to detect and mitigate such advanced threats. Regular updates, employee training, and advanced threat detection tools are essential in safeguarding against these sophisticated attacks.

Additional Resources

For further insights, check:

• The Hacker News

References

1. Thorve, Akshay (2025). “Fileless Remcos RAT Delivered via LNK Files and MSHTA in PowerShell-Based Attacks”. The Hacker News. Retrieved 2025-05-16. ↩︎