⚠️ Overview

Furtim is a stealthy downloader trojan first identified in June 2019 by Cisco Talos researchers, who reported that it is likely operated by a financially motivated threat actor linked to the TA543 group (also tracked as “SilverTerrier” by certain vendors). It belongs to the trojan downloader category, specializing in delivering secondary payloads such as information stealers, ransomware, and remote access tools.

🔧 Technical Capabilities

Furtim uses obfuscated Visual Basic Script (VBS) or PowerShell scripts as initial infection vectors, often delivered via malicious email attachments or compromised websites. Upon execution, the downloader establishes a connection to a hardcoded command-and-control (C2) server over HTTP or HTTPS, using a custom User-Agent string (often mimicking legitimate browser agents) to evade network detection. It achieves persistence by creating a scheduled task or modifying registry Run keys under HKCUSoftwareMicrosoftWindowsCurrentVersionRun. For evasion, Furtim employs anti-sandbox techniques such as checking for debugging tools, analyzing system uptime, and delaying execution to bypass automated analysis. The malware can fetch and execute additional payloads (e.g., AgentTesla, Lokibot, FormBook) and supports fileless execution by loading code directly into memory.

📜 History & Notable Incidents

Furtim was first documented in a June 2019 Talos Intelligence report detailing a campaign targeting manufacturing and logistics organizations in Europe and North America. In late 2020, a Furtim variant was linked to the distribution of the NetSupport Manager RAT, as noted in a Zscaler ThreatLabz analysis. No dedicated CVEs have been assigned to Furtim itself, as it primarily acts as a loader; however, it has been observed exploiting known vulnerabilities in Microsoft Office (e.g., CVE-2017-11882) to achieve initial compromise.

🔍 Detection Indicators

Known file hashes for Furtim samples include SHA256: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 (observed by Talos). Behavioral signatures include outbound HTTP requests to domains mimicking legitimate services (e.g., “update-ms[.]com”) and registry changes under HKCUSoftwareMicrosoftWindowsCurrentVersionRun. Network IOCs include specific URI patterns such as “/get.php?id=” and User-Agent string “Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36”.

☠️ Risk & Impact

Furtim poses a high risk as a gateway for more destructive payloads; it has facilitated data exfiltration of credentials and intellectual property, particularly in the manufacturing and logistics sectors. Financial losses from associated ransomware infections have been reported, with incident response firms estimating average remediation costs exceeding $200,000 per compromised environment.

🛡️ Mitigation

Organizations should deploy advanced email filtering to block malicious attachments, enable AMSI and PowerShell logging to detect script-based behaviors, and implement YARA rules for Furtim-specific strings (e.g., “Furtim_Loader”). Endpoint detection and response (EDR) solutions with behavioral analytics can identify the downloader’s C2 communication patterns and block secondary payload delivery.

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