Ukrainian Hacker Network Launches Massive VPN Infrastructure Attacks
Critical Security Alert
Active brute-force campaign targeting SSL VPN and RDP devices with connections to major ransomware groups.
A Ukrainian-based hacker network known as FDN3 has been conducting large-scale brute-force attacks against SSL VPN and RDP devices throughout 2025. The campaign, which peaked in July but continues into September, has direct connections to major ransomware groups including Black Basta and RansomHub.
Attack Campaign Details
The FDN3 network has been systematically targeting VPN infrastructure using sophisticated methods:
- SSL VPN Exploitation: Brute-force attacks on enterprise VPN gateways
- RDP Targeting: Remote Desktop Protocol credential stuffing campaigns
- Ransomware Delivery: Initial access for Black Basta and RansomHub operations
- Credential Harvesting: Stolen credentials sold on dark web marketplaces
UK Impact Assessment
UK Businesses at Risk
- • Corporate VPN endpoints under active attack
- • Financial services sector particularly targeted
- • Healthcare organizations reporting increased attempts
- • Critical infrastructure facilities on high alert
Ransomware Connection
Intelligence sources have confirmed direct links between FDN3 and major ransomware operations:
- Black Basta: Using compromised VPN access for network infiltration
- RansomHub: Leveraging stolen credentials for lateral movement
- Access Brokerage: Selling VPN access to multiple cybercriminal groups
- Double Extortion: Data theft preceding encryption attacks
Immediate Protection Measures
Essential Security Steps:
- • Enable multi-factor authentication on all VPN accounts
- • Implement strong, unique passwords for VPN services
- • Monitor VPN access logs for suspicious activity
- • Update VPN software to latest security patches
- • Consider IP whitelisting for corporate VPN access
- • Deploy network segmentation to limit breach impact
VPN Provider Response
Major VPN providers have implemented enhanced security measures in response to the ongoing attacks:
- Increased monitoring of authentication attempts
- Enhanced anomaly detection systems
- Mandatory security updates for enterprise clients
- Additional verification requirements for suspicious logins
Expert Recommendations
Cybersecurity experts recommend UK organizations take immediate action:
Best Practices:
- • Conduct immediate VPN security audits
- • Implement zero-trust network architecture
- • Regular penetration testing of VPN infrastructure
- • Employee training on social engineering tactics
- • Incident response plan testing and updates
Ongoing Monitoring
The FDN3 campaign represents a significant and ongoing threat to UK cybersecurity. Organizations using VPN services should maintain heightened security postures and work closely with cybersecurity providers to ensure adequate protection against these sophisticated attacks.