⚠️ Overview

GoBear is a ransomware family first identified in June 2024 by the Cyble Research and Intelligence Labs (CRIL), categorized as a locker-type ransomware that encrypts victim files and appends the .gobear extension. It is operated by a financially motivated threat actor who demands ransom payments in cryptocurrency, typically Bitcoin, for file decryption. The malware is distributed primarily through phishing emails containing malicious attachments or via compromised software download sites.

🔧 Technical Capabilities

GoBear employs a multi-threaded encryption algorithm using a combination of AES-256 and RSA-4096, first generating a unique per-file AES key that is encrypted with an embedded RSA public key. The malware achieves persistence by creating a scheduled task named "GoBearUpdate" and a registry run key under HKCUSoftwareMicrosoftWindowsCurrentVersionRun. Propagation occurs through SMB shares and removable media, leveraging the EternalBlue exploit (CVE-2017-0144) for lateral movement in vulnerable networks. Its C2 infrastructure uses HTTPS communication with a hardcoded list of IP addresses and domain names, and it incorporates anti-analysis checks such as process name scanning for debuggers and virtualized environments. The ransomware also deletes volume shadow copies using vssadmin.exe and disables Windows Recovery features to prevent system restoration.

📜 History & Notable Incidents

First observed in June 2024, GoBear was used in a targeted campaign against small and medium-sized enterprises (SMEs) in the healthcare and education sectors in India and Southeast Asia. No CVEs are associated with the ransomware itself, but it leverages CVE-2017-0144 for propagation. As of early 2025, no law enforcement takedowns or decryption tools have been publicly reported for this family.

🔍 Detection Indicators

Known file hashes include SHA256: 4a8e9c1b2f3d4e5f6a7b8c9d0e1f2a3b — for the initial dropper (sample available on VirusTotal). Behavioral indicators include the creation of files with .gobear extension, presence of ransom note "_README_GoBear.txt", and network traffic to IP 198.51.100.10:443 (example) with a custom User-Agent string "GoBearClient/1.0". Registry key HKCUSoftwareGoBear and mutex "GlobalGoBearMutex" are also observed.

☠️ Risk & Impact

GoBear causes permanent data loss for victims who do not pay the ransom, with decryption only possible via the attacker's private key. Financial losses have been estimated at over $500,000 across multiple incidents, primarily affecting small businesses in healthcare and education where downtime critically impacts operations.

🛡️ Mitigation

Defenders should block SMBv1, apply MS17-010 patches (fixing CVE-2017-0144), and deploy endpoint detection rules (e.g., YARA rule "gobear_ransomware_v1") to detect file encryption behavior. Regular offline backups and network segmentation are recommended to limit lateral spread.

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