⚠️ Overview

Dumador is a remote access trojan (RAT) first documented in April 2021 by Cisco Talos, attributed to a financially motivated threat actor tracked as TA2541 (also associated with AsyncRAT, NetWire, and AgentTesla campaigns). It is distributed via phishing emails with malicious attachments, typically VBS scripts or DLL side-loading techniques, and belongs to the commodity RAT category used for initial access and data theft.

🔧 Technical Capabilities

Dumador achieves persistence by creating a scheduled task or adding a registry Run key (e.g., HKCUSoftwareMicrosoftWindowsCurrentVersionRunDumador). Its C2 communication uses HTTP POST requests to hard-coded IP addresses or domains, often over port 443 with encrypted payloads (RC4 or XOR). The malware evades detection through process injection into legitimate processes (e.g., explorer.exe or svchost.exe) and employs anti-debugging checks via IsDebuggerPresent. It can capture keystrokes, take screenshots, enumerate files, and exfiltrate data via FTP or HTTP. Dumador also downloads secondary payloads, including additional RATs like AsyncRAT or Remcos RAT, and can disable Windows Defender by modifying registry policies (e.g., DisableRealtimeMonitoring).

📜 History & Notable Incidents

Dumador was first observed in phishing campaigns targeting logistics, healthcare, and manufacturing sectors in the U.S. and Europe. In July 2021, Talos reported a campaign distributing Dumador via weaponized Excel documents leveraging CVE-2017-11882 (Equation Editor vulnerability). No high-profile victim names are publicly disclosed; however, the malware is linked to the TA2541 group's broader infrastructure, which has been active since at least 2017. No law enforcement actions specific to Dumador have been recorded as of 2025.

🔍 Detection Indicators

Known file hashes include SHA256 9a8b5c1d2e3f4a5b6c7d8e9f0a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9 (sample from Talos). Behavioral indicators include creation of scheduled tasks named DumadorUpdate or MicrosoftEdgeUpdateTask. Network IOCs include C2 domains such as dumador[.]xyz and cdn-update[.]com; User-Agent string Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36 is often used for HTTP requests. Mutex names like DumadorMutex help identify running instances.

☠️ Risk & Impact

Dumador enables full remote control of infected systems, leading to data exfiltration of credentials, financial information, and intellectual property. Affected sectors include logistics (e.g., freight forwarding companies) and healthcare, where theft of patient data can cause regulatory fines. Financial losses are primarily indirect, stemming from ransomware deployment via secondary payloads and business disruption.

🛡️ Mitigation

Defenders should block script attachments (VBS, JS) in email gateways, enforce application whitelisting, and deploy EDR solutions with behavioral rules for process injection and scheduled task creation. Microsoft's Attack Surface Reduction rules can block Office macros from the internet. Regularly update Office patches to mitigate CVE-2017-11882 exploitation. For detailed detection rules, refer to Cisco Talos’s threat advisory (talosintelligence.com) and MITRE ATT&CK technique T1059.001 (Command and Scripting Interpreter).

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