Remcos RAT (Remote Access Trojan) is a commercially available malware tool that enables attackers to remotely control infected Windows systems. The campaign identified on 2020-02-28 involves the distribution of Remcos RAT primarily through malspam campaigns leveraging spearphishing attachments (MITRE ATT&CK T1193). The malware employs multiple techniques to evade detection and maintain persistence, including scripting (T1064), registry run keys or startup folder modifications (T1060), timestomping to alter file timestamps (T1099), masquerading as legitimate files or processes (T1036), and indirect command execution (T1202). It also uses uncommonly used ports (T1065) for command and control communications and indicator blocking (T1054) to hinder forensic analysis and detection. Despite its low severity classification in this report, Remcos RAT is a versatile and stealthy tool that can facilitate espionage, data exfiltration, credential theft, and lateral movement within compromised networks. The campaign does not specify affected software versions or known exploits in the wild, indicating that the infection vector relies on social engineering rather than exploiting software vulnerabilities. The threat level is moderate (3/10), with no direct evidence of widespread exploitation but with significant potential for targeted attacks. The lack of CVSS score necessitates an independent severity assessment based on the malware's capabilities and attack techniques.

For European organizations, Remcos RAT poses a significant risk primarily through spearphishing attacks that can lead to unauthorized remote access to critical systems. Successful infections can compromise confidentiality by enabling attackers to steal sensitive data, including intellectual property, personal data protected under GDPR, and credentials. Integrity may be affected if attackers modify or delete data or system configurations. Availability could be impacted if attackers disrupt services or deploy additional payloads such as ransomware. The stealthy nature of Remcos RAT, including timestomping and masquerading, complicates detection and incident response efforts. European organizations in sectors such as finance, government, healthcare, and critical infrastructure are particularly at risk due to the high value of their data and the potential geopolitical motivations behind attacks. The use of uncommonly used ports and indirect command execution techniques may bypass traditional network defenses, increasing the likelihood of successful persistence and lateral movement within enterprise networks.

To mitigate the risk posed by Remcos RAT campaigns, European organizations should implement targeted measures beyond generic advice: 1) Enhance email security by deploying advanced anti-phishing solutions that analyze attachments and embedded scripts for malicious behavior, including sandboxing and attachment detonation. 2) Enforce strict execution policies for scripting environments such as PowerShell and Windows Script Host to restrict unauthorized script execution. 3) Monitor and audit registry run keys and startup folders for unauthorized modifications, employing endpoint detection and response (EDR) tools capable of detecting persistence mechanisms. 4) Implement network segmentation and monitor for unusual outbound traffic on non-standard ports to detect and block command and control communications. 5) Deploy file integrity monitoring to detect timestomping and masquerading attempts, correlating with behavioral analytics to identify anomalies. 6) Conduct regular user awareness training focused on spearphishing recognition and reporting. 7) Maintain up-to-date endpoint protection solutions with capabilities to detect indicator blocking and indirect command execution techniques. 8) Establish robust incident response plans that include forensic analysis procedures to counteract indicator blocking and timestomping tactics.