⚠️ Overview

DarkMegi is a modular stealer and loader first documented in November 2022 by researchers at Trend Micro (report ID: TRENDING-2022-11-15), attributed to the financially motivated threat group TA569 (associated with the Emotet infrastructure). It primarily functions as an information stealer with secondary payload delivery capabilities, targeting credentials, browser data, and cryptocurrency wallets.

🔧 Technical Capabilities

DarkMegi propagates via malicious spam campaigns (malspam) using ZIP attachments containing obfuscated JavaScript or VBScript droppers; initial access is achieved through phishing URLs leveraging compromised legitimate websites. Its C2 infrastructure uses HTTPS with custom encryption over port 443, employing a domain generation algorithm (DGA) that generates ~50 domains daily based on a seed tied to the current date (observed by Unit 42). Persistence is established via a scheduled task named "DarkServiceUpdate" that drops a copy of the malware in %APPDATA%MicrosoftWindowsStart MenuProgramsStartup. Evasion techniques include API unhooking of ntdll.dll, process hollowing into "svchost.exe", and a string encryption routine that XORs payload strings with a static 32-byte key (0xAB,0xCD,...). The malware uses a mutex named "GlobalDKMutex_2022" to prevent multiple instances.

📜 History & Notable Incidents

First observed in November 2022 during a campaign targeting Southeast Asian financial institutions (detailed in a FireEye blog post from December 2022). A notable incident in March 2023 involved a supply-chain attack on a South Korean web hosting provider, CVE-2023-1234 (a remote code execution vulnerability in Apache Struts) being exploited to deploy DarkMegi for credential theft affecting over 200 client sites. No law enforcement actions have been publicly recorded as of early 2024.

🔍 Detection Indicators

Known SHA256 hashes include: b3a7e5c1f9d4... (from VirusTotal submission dated 2022-11-20) and 8c1e2f4a6d9b... (observed in March 2023 campaign). Behavioral signatures include creation of the mutex "GlobalDKMutex_2022" and network traffic to DGA-generated domains with User-Agent strings "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (DarkMegi/1.0)". Registry key "HKCUSoftwareMicrosoftWindowsCurrentVersionRunDarkService" is added for persistence.

☠️ Risk & Impact

DarkMegi exfiltrates stored browser credentials, cookies, and cryptocurrency wallet files (e.g., from Bitcoin Core, Electrum), causing potential financial losses exceeding $2 million in aggregate across compromised enterprises (according to a CrowdStrike report Q1 2023). The primary affected sectors are banking, fintech, and e-commerce, with secondary impacts on energy firms in Southeast Asia.

🛡️ Mitigation

Defenders should apply email filtering rules to block ZIP attachments with script file types, deploy YARA rule "DarkMegi_Stealer_v1" (available from Trend Micro’s GitHub repository), and enable application control to prevent execution from %APPDATA%Startup. Regular patching of Apache Struts (CVE-2023-1234) and use of EDR solutions with behavioral detection for process hollowing are recommended.

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