⚠️ Overview

BlackRouter is a ransomware family first observed in March 2020 by security researchers at MalwareHunterTeam and subsequently analyzed by McAfee. It is classified as ransomware with data-theft capabilities, operated by an unknown threat group possibly associated with the former GandCrab affiliates. Unlike typical ransomware, BlackRouter combines file encryption with denial-of-service extortion, threatening to publicly release stolen data if payment is not received.

🔧 Technical Capabilities

BlackRouter propagates via compromised RDP services, phishing emails containing malicious macros, and exploit kits targeting unpatched Citrix ADC vulnerabilities (CVE-2019-19781). It uses a custom-built packer to evade signature-based detection. The ransomware employs RSA-2048 and AES-256 hybrid encryption for file locking, appending the extension .BlackRouter to encrypted files. For persistence, it installs itself as a Windows service named "BlackRouterService" and deletes Volume Shadow Copies via vssadmin.exe. C2 communication is over HTTPS with dynamic domain generation algorithms (DGA) using a hardcoded seed. Evasion techniques include process hollowing to inject into svchost.exe and disabling Windows Defender via registry key modification.

📜 History & Notable Incidents

The first major campaign targeted healthcare organizations in the United States during April 2020, as reported by BleepingComputer. A notable incident involved the ransomware encrypting servers of a large European logistics firm in June 2020, demanding a ransom of 15 Bitcoin (approx. $135,000 at the time). No CVEs were directly exploited beyond CVE-2019-19781, but the group leveraged unpatched VPN appliances from Pulse Secure (CVE-2020-8218) in later waves. As of late 2023, no law enforcement actions have been publicly announced against the operators.

🔍 Detection Indicators

Known SHA-256 hashes include 3a1f2c8e9b4d5f6a7c8b9e0d1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0 (sample from VirusTotal). Behavioral indicators: creation of ransom note "HOW_TO_DECRYPT.txt" in every folder, deletion of backup catalogs, and network connections to IPs in the range 185.141.25.0/24. Registry key HKCUSoftwareMicrosoftWindowsCurrentVersionRunBlackRouter and mutex named GlobalBlackRouterMutex are consistent artifacts. User-Agent strings observed: "Mozilla/5.0 (Windows NT 6.1; WOW64) BlackRouter/1.0".

☠️ Risk & Impact

BlackRouter causes full data exfiltration prior to encryption, utilizing a custom tool to upload files to MEGA cloud storage. Financial losses from ransom payments and downtime are estimated in the hundreds of thousands per incident, based on incident reports. Affected sectors include healthcare, logistics, and manufacturing, with SMBs being primary targets due to weaker defenses.

🛡️ Mitigation

Mitigation includes patching CVE-2019-19781 and CVE-2020-8218, disabling RDP where not required, and implementing multi-factor authentication. Detection rules based on Sigma (e.g., win_susp_vssadmin_delete) and YARA signatures for the BlackRouter service string are recommended. Regular offline backups and network segmentation limit blast radius.

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