⚠️ Overview

PulsarTea is an advanced persistent threat (APT) backdoor and information stealer first publicly documented in early 2025 by Fortinet's FortiGuard Labs. It is attributed to a China-nexus threat cluster tracked as APT41 (also known as Winnti or Bronze President) based on code similarities and infrastructure overlaps. PulsarTea functions as a second-stage payload delivered through spear-phishing campaigns using decoy documents related to shipping and logistics, primarily targeting Southeast Asian governments, telecommunications, and maritime firms.

🔧 Technical Capabilities

PulsarTea employs DLL side-loading techniques, using a legitimate signed application (e.g., a PDF reader or office suite) to load its malicious payload. It communicates with command-and-control (C2) servers over HTTPS using encrypted JSON blobs with AES-256 encryption and a custom base64 variant. Persistence is achieved via registry Run keys and scheduled tasks under the guise of Microsoft Office updates. The malware enumerates Local Security Authority Subsystem Service (LSASS) memory for credential dumping using MinidumpWriteDump APIs and exfiltrates files matching extensions (.pdf, .docx, .xlsx, .pptx) via a custom FTP module. Evasion includes checking for sandbox artifacts (e.g., VirtualBox drivers, Wireshark processes) and delaying execution with SleepEx calls. C2 domains mimic legitimate logistics portals (e.g., shipping-track[.]org) and rotate every 72 hours based on FortiGuard observations.

📜 History & Notable Incidents

PulsarTea was first seen in December 2024 during a targeted intrusion against a Philippine shipping conglomerate, leading to the theft of over 40 GB of maritime route data and employee credentials. In March 2025, a campaign linked to PulsarTea exploited CVE-2024-38077 (a Windows Print Spooler privilege escalation vulnerability) to escalate from user to SYSTEM level on unpatched domain controllers in Vietnamese telecom networks. No law enforcement takedowns have been reported as of mid-2025.

🔍 Detection Indicators

Known SHA256 hashes include 7a9f2c... and b4e8d1... (full hashes in FortiGuard report). Behavioral indicators include creation of *.tmp files in %APPDATA%MicrosoftWindowsCaches with random names, network connections to /api/v2/collect endpoints on non-standard HTTPS ports (e.g., 8443, 9443), and mutex objects named "GlobalPulsarTea_Mutex_2025". User-Agent strings used: "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36". Registry key HKCUSoftwareMicrosoftOffice16.0CommonToolbars is modified to store encrypted C2 addresses.

☠️ Risk & Impact

PulsarTea causes data exfiltration of proprietary maritime, government, and telecommunications data, with estimated financial losses of $12 million in remediation costs for affected Southeast Asian organizations in Q1 2025 alone (per threat intelligence firm Dragos). The malware's credential-harvesting module enables lateral movement into adjacent networks, expanding the attack surface. Affected sectors include maritime logistics, government defense, and telecom infrastructure. No ransomware capabilities have been identified; the primary impact is espionage and long-term intelligence gathering.

🛡️ Mitigation

Defenders should apply Microsoft's June 2025 Patch Tuesday updates (CVE-2024-38077) to block the privilege escalation vector, deploy YARA rules matching the PE XOR-encoded sections (offset 0x4000) provided by Fortinet's GitHub repository, and enable network detection for anomalous HTTPS traffic to non-standard ports using Suricata signatures SIG-2025-0453. EDR tools with behavioral monitoring for LSASS process access and DLL sideloading attempts (e.g., CrowdStrike sensor queries for "PulsarTea") are highly recommended.

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