The APT36 malware campaign is a targeted threat operation that utilizes a combination of social engineering and technical evasion techniques to infiltrate victim networks. The primary infection vector is phishing (MITRE T1566), where malicious desktop entry files are delivered to victims, often via Google Drive links, to bypass traditional email filtering and security controls. These desktop entry files act as a launcher for malicious scripts (T1064) that execute payloads on the victim’s system. The malware employs masquerading (T1036) and hides files and directories (T1564.001) to evade detection. Persistence is achieved through the creation or manipulation of Windows services (T1543.003), allowing the malware to survive reboots and maintain control. The attackers use binary padding (T1027.001) to obfuscate payloads and avoid signature-based detection. Brute force techniques (T1110) are used to gain access to additional systems or escalate privileges. The campaign also involves software discovery (T1518) to map the environment and identify valuable targets. Communication with command and control servers occurs over both application layer protocols (T1071) and non-application layer protocols (T1095), often utilizing non-standard ports (T1571) to evade network monitoring. Tools and additional payloads are transferred using ingress tool transfer techniques (T1105). The campaign is linked to the threat actor group Operation C-Major, known for targeting South Asian and European entities. No patches or direct fixes exist for this campaign, as it relies on social engineering and custom malware rather than exploiting software vulnerabilities. The campaign’s complexity and use of multiple evasion techniques make it a persistent threat requiring layered defense strategies.

For European organizations, the APT36 campaign poses a significant risk to confidentiality, integrity, and availability of critical systems. The use of phishing and social engineering increases the likelihood of initial compromise, especially in sectors with less mature cybersecurity awareness. Once inside, the malware’s persistence mechanisms and network reconnaissance capabilities enable lateral movement and data exfiltration, potentially leading to intellectual property theft, espionage, or disruption of services. Critical infrastructure, government agencies, and organizations handling sensitive data are at heightened risk due to the strategic interest of the threat actor. The campaign’s use of cloud services like Google Drive for payload delivery complicates detection and response, as these services are commonly trusted and widely used. The medium severity rating reflects the campaign’s targeted nature and requirement for user interaction, but the potential for significant operational and reputational damage remains high. European entities with extensive use of Windows environments and reliance on cloud collaboration tools are particularly vulnerable.

1. Implement advanced email filtering and phishing detection solutions that specifically scan for malicious desktop entry files and suspicious links, including those hosted on cloud platforms like Google Drive. 2. Conduct regular user awareness training focused on recognizing phishing attempts and the risks of opening unknown files or links, emphasizing the threat of desktop entry files as malware vectors. 3. Monitor endpoint systems for creation or modification of Windows services and hidden files/directories, using behavioral analytics to detect masquerading and persistence techniques. 4. Restrict or monitor the use of cloud storage services for inbound payload delivery, employing data loss prevention (DLP) and cloud access security broker (CASB) solutions to control and inspect file transfers. 5. Enforce strong authentication and account lockout policies to mitigate brute force attacks, and implement network segmentation to limit lateral movement. 6. Deploy network monitoring tools capable of detecting anomalous traffic on non-standard ports and unusual protocol usage, correlating with known indicators of ingress tool transfer and command and control communications. 7. Maintain up-to-date threat intelligence feeds and integrate them into security operations to identify emerging TTPs related to Operation C-Major and APT36. 8. Conduct regular security assessments and penetration testing to identify and remediate gaps in phishing resilience and endpoint security controls.