A sophisticated ransomware strain known as Gunra has emerged as a critical threat to organizations worldwide since April 2025. Written in C/C++ and believed to be based on the Conti ransomware source code, Gunra employs advanced double-extortion tactics, encrypting victims’ files while simultaneously exfiltrating sensitive data for public exposure threats. The ransomware has successfully targeted over 11 high-profile organizations across manufacturing, healthcare, technology, and consumer services sectors in Brazil, Japan, Egypt, Panama, Italy, and the UAE. Gunra’s sophisticated attack methodology includes advanced evasion techniques, anti-debugging capabilities, and the systematic deletion of shadow copies to prevent recovery, making it a formidable threat requiring immediate organizational attention and defensive measures.
Gunra ransomware represents a significant evolution in ransomware sophistication, first observed on April 23, 2025. The malware is written in C/C++ and exhibits characteristics suggesting it may be based on the leaked Conti ransomware source code. Upon successful system compromise, Gunra executes a multi-stage attack process designed to maximize damage and prevent recovery.
The ransomware begins by enumerating running processes and collecting comprehensive system information through reconnaissance activities. It employs advanced anti-analysis techniques, utilizing the IsDebuggerPresent API to detect debugging environments and evade security research efforts. The malware uses GetCurrentProcess and TerminateProcess functions for process manipulation and privilege escalation, allowing it to inject malicious code into other processes and disable security tools.
Gunra’s file discovery capabilities are implemented through FindNextFileExW and related APIs, systematically searching directories for target file extensions including .docx, .pdf, .xls, .jpg, and numerous other document and media formats. The ransomware creates a process named ‘gunraransome.exe’ visible in Task Manager and proceeds to delete available shadow copies using Windows Management Instrumentation (WMI) utilities, effectively disabling system restore capabilities.
The encryption process appends a ‘.ENCRT’ extension to all encrypted files and drops ransom notes named ‘R3ADM3.txt’ in every affected directory. The ransom notes indicate that sensitive data has been both encrypted and exfiltrated, with attackers threatening public release on underground forums if demands are not met within a five-day deadline. Communication with victims occurs through Tor-based negotiation portals styled similarly to messaging applications like WhatsApp, complete with assigned roles such as “Manager.”
Recent intelligence indicates Gunra has targeted a healthcare organization in the UAE, threatening to publish a database containing sensitive information of 450 million patients by June 8, 2025, demonstrating the severe potential impact of these attacks.
Who is the Gunra Ransomware Group?
The Gunra Ransomware Group emerged in April 2025 as a financially motivated threat actor employing sophisticated double-extortion tactics. The group has demonstrated rapid operational scaling, successfully compromising 11 high-profile organizations across multiple critical sectors within their first two months of observed activity.
The group’s operational methodology suggests a well-organized cybercriminal enterprise with established infrastructure and systematic targeting approaches. Their use of Tor-based negotiation portals with professional interfaces and assigned roles indicates a mature operational structure designed for sustained criminal activity.
Gunra’s targeting strategy focuses on high-value organizations across manufacturing, healthcare, technology, and consumer services sectors, with confirmed victims spanning Brazil, Japan, Egypt, Panama, Italy, and the UAE. This global reach suggests either a distributed operational model or sophisticated remote access capabilities enabling worldwide targeting from centralized command structures.
Gunra's Sophisticated Global Campaign:
The Gunra ransomware campaign represents a significant escalation in ransomware sophistication and global reach. The group’s rapid emergence and successful targeting of major organizations across multiple continents demonstrate advanced operational capabilities and strategic planning.
The ransomware’s technical sophistication, including its anti-analysis features, systematic shadow copy deletion, and advanced encryption implementation, suggests access to skilled developers and potentially leaked source code from established ransomware families. The group’s double-extortion model, combining file encryption with data theft and public exposure threats, maximizes pressure on victims and potential financial returns.
Recent targeting of healthcare infrastructure, particularly the threatened exposure of 450 million patient records, demonstrates the group’s willingness to target critical infrastructure and sensitive personal data, raising concerns about potential national security implications and public safety risks.
The Challenges of Removal and Recovery:
Gunra ransomware can be removed using trusted antivirus or malware removal tools, but this only stops further damage—it doesn’t decrypt files. Once encrypted, data can typically only be restored with a valid decryption key held by the attacker. This highlights the importance of preventive measures, especially regular, secure backups stored offline or in encrypted cloud environments. In the absence of backups, recovery is rarely possible unless the ransomware has known flaws or a public decryption tool exists.
Infection Vectors: How Gunra Enters Systems:
Gunra ransomware spreads through multiple attack vectors, with phishing emails being the most common often disguised as legitimate messages containing malicious attachments or links. It can also infect systems via drive-by downloads, malvertising, fake software updates, or pirated applications. Gunra often hides in common file formats like PDFs, Word documents, or ZIP archives, exploiting system vulnerabilities or macros upon opening. In some cases, it can propagate across local networks or external drives, rapidly spreading and amplifying the impact.
*Refer to appendix 1 for more details
Staying Protected:
Given the severity of ransomware like Gunra and the difficulty of file recovery, prevention is critical. A layered security approach is essential using updated antivirus software, applying regular system patches, and implementing email filters to block phishing. Equally important is user training to recognize and avoid suspicious emails or links. Backups must be treated as vital assets: performed regularly, stored separately, and tested for reliability. Gunra underscores the broader risks of ransomware, from financial loss to data compromise making vigilance, education, and preparation key to defense.
Gunra ransomware attacks result in severe organizational and operational impacts including:• Complete system encryption preventing access to critical business data and applications• Exfiltration of sensitive organizational and customer data with public exposure threats• Disruption of business operations and potential extended downtime• Significant financial losses from ransom demands, recovery costs, and business interruption• Reputational damage from data breaches and operational disruptions• Potential regulatory compliance violations and associated penalties• Long-term recovery challenges due to systematic backup deletion• Increased cybersecurity insurance premiums and potential coverage limitations
Immediate Response Actions:
• Block all identified threat indicators across security controls and network infrastructure
• Conduct comprehensive IOC searches across organizational environments using available security tools
• Isolate any infected systems immediately to prevent lateral movement and further encryption
• Disconnect compromised devices from internet and local network connections
• Implement emergency backup restoration procedures from clean, offline backup systems
Enhanced Security Measures:
• Deploy advanced Endpoint Detection and Response (EDR) solutions with behavioral analysis capabilities
• Implement real-time file integrity monitoring to detect unauthorized encryption activities
• Enable comprehensive WMI activity monitoring, particularly for shadow copy deletion attempts
• Strengthen network segmentation to limit ransomware propagation and lateral movement
• Deploy anti-ransomware solutions with real-time encryption detection and prevention
Access Control and Authentication:
• Enforce multi-factor authentication (MFA) across all user accounts and administrative access
• Implement strict least-privilege access controls for all users and service accounts
• Reset all user credentials, particularly privileged and administrative account passwords
• Review and restrict administrative privileges to essential personnel only
Backup and Recovery Enhancement:
• Maintain regular offline backups stored in isolated, air-gapped environments
• Test backup integrity and restoration procedures regularly to ensure reliability
• Implement immutable backup solutions to prevent ransomware encryption or deletion
• Develop and regularly test comprehensive disaster recovery and business continuity plans
Security Awareness and Training:
• Conduct immediate security awareness training focusing on phishing recognition and prevention
• Educate employees on social engineering tactics commonly used in ransomware campaigns
• Implement regular security training programs with simulated phishing exercises
• Establish clear incident reporting procedures for suspicious activities
Vulnerability Management:
• Apply all available security patches and updates across operating systems and applications
• Conduct comprehensive vulnerability assessments to identify and remediate security gaps
• Implement automated patch management systems for critical security updates
• Regularly audit and update security configurations across all systems
https://www.cyfirma.com/research/gunra-ransomware-a-brief-analysis/
https://socprime.com/blog/detect-gunra-ransomware/
https://gbhackers.com/gunra-ransomwares-double%E2%80%91extortion-playbook/
