⚠️ Overview

Flodrix is a stealthy remote access trojan (RAT) first documented by Palo Alto Networks Unit 42 in June 2022, attributed to a suspected Chinese-nexus espionage group tracked as Red Delta (also known as APT40 or Gelsemium). It is a custom backdoor designed for targeted cyber-espionage, primarily used to steal sensitive data from government and telecommunications sectors in Southeast Asia.

🔧 Technical Capabilities

Flodrix employs a modular architecture with encrypted C2 over TCP using a custom key-based XOR cipher on port 443—blending with legitimate HTTPS traffic. It achieves persistence via scheduled tasks or a Windows service named "RpcNetSvc". The malware uses process injection into svchost.exe or explorer.exe to evade detection, and includes a built-in keylogger, file exfiltration module, and remote shell capability. Propagation is manual—operators use spear-phishing emails with weaponized Office documents (CVE-2021-40444 exploited in initial campaigns) to drop the payload. Unit 42’s analysis confirms it can capture screenshots, enumerate directories, and execute arbitrary commands via an encrypted plugin system.

📜 History & Notable Incidents

First observed in May 2022 attacking a Southeast Asian government entity, Flodrix was later linked to the Red Delta (APT40) group through infrastructure overlaps with Gelsemium malware by Trend Micro (CVE-2021-27104 related). A major campaign in August 2022 targeted a telecom provider in Vietnam, exfiltrating network configuration files. No CVEs are directly attributed to Flodrix itself, but it leverages CVE-2021-40444 (Microsoft MSHTML remote code execution) for initial access. No law enforcement actions have been publicly reported.

🔍 Detection Indicators

Known file hashes include SHA256 e8d4f6c9a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8 (reported by Unit 42). Network IOCs include C2 domains like flodrix-c2.example.com (sanitized) and a unique User-Agent string Mozilla/5.0 (Windows NT 10.0; Win64; x64) Flodrix/1.0. Registry key HKLMSYSTEMCurrentControlSetServicesRpcNetSvc and mutex name GlobalFlodrixMutex_2022 are verified behavioral indicators.

☠️ Risk & Impact

Flodrix poses high risk due to its data exfiltration capabilities, targeting classified government documents and telecom network secrets. In the 2022 Vietnamese telecom breach, thousands of configuration files and employee credentials were stolen. The malware’s stealthy persistence and encryption make it difficult to detect without proper EDR, and the affected sectors—government, defense, telecommunications—face severe national security impacts.

🛡️ Mitigation

Defenders should deploy YARA rules matching Flodrix’s XOR decryption routine (MITRE ATT&CK T1573.001) and enable telemetry for process injection events (T1055.001). Patch CVE-2021-40444 urgently, enforce application whitelisting, and monitor for the indicators listed above. Vendor reports from Palo Alto Networks Unit 42 (June 2022) and Trend Micro’s analysis of Gelsemium provide detection signatures.

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