Unleashing the Kraken Ransomware Group
Summary:
Kraken is a Russian-speaking ransomware group that emerged in early 2025 from the remnants of the HelloKitty cartel, adopting the same double-extortion model and even reusing HelloKitty’s ransom note filename. The group conducts opportunistic big-game hunting attacks across multiple regions, including the U.S., U.K., Canada, Denmark, Panama, and Kuwait, with ransom demands reaching $1M in Bitcoin. In August 2025, Cisco Talos observed Kraken exploiting exposed SMB vulnerabilities for initial access, followed by credential harvesting, re-entry via RDP using stolen admin accounts, and establishing persistence with Cloudflared reverse tunnels. The actor used SSHFS to explore the environment and exfiltrate data before deploying the Kraken ransomware binary and moving laterally via RDP to additional systems.
Kraken operates as a cross-platform ransomware family, with dedicated encryptors for Windows, Linux, and VMware ESXi. It supports extensive command-line options, full or partial encryption, SQL and network share targeting, and capabilities specifically designed for enterprise environments. A notable feature is Kraken’s encryption benchmarking, where the malware measures system throughput to choose between full or partial encryption, an uncommon characteristic in ransomware operations. The Windows encryptor includes anti-reinfection logic, WoW64 redirection manipulation, privilege escalation, SQL/Hyper-V/drive encryption modules, and extensive anti-analysis measures such as control-flow obfuscation, sleep delays, suppression of error dialogs, VSS deletion, and service disabling.
Security Officer Comments:
The Linux/ESXi encryptor includes platform detection (ESXi, Nutanix, Synology, Ubuntu), forceful VM termination, daemonized execution, control-flow obfuscation, and a multi-stage cleanup process using a self-deleting bash script to erase forensic traces. Kraken’s encrypted files use the .zpsc extension and victims receive a ransom note titled readme_you_ws_hacked.txt. The group also launched a new cybercrime forum, The Last Haven Board, from its leak site, with purported support from HelloKitty and WeaCorp, reinforcing links between these actors and signaling an attempt to expand its underground influence. Kraken demonstrates a level of maturity and enterprise-aware tradecraft that strongly aligns with its suspected lineage from HelloKitty. Its operational behavior, particularly the use of Cloudflared tunnels, SSHFS-based exfiltration, VM termination, and multi-platform encryptors, shows it is built for full intrusion operations rather than simple smash-and-grab ransomware deployment.
Suggested Corrections:
Backup your data, system images, and configurations, regularly test them, and keep the backups offline: Ensure that backups are regularly tested and that they are not connected to the business network, as many ransomware variants try to find and encrypt or delete accessible backups. Maintaining current backups offline is critical because if your network data is encrypted with ransomware, your organization can restore systems.
Update and patch systems promptly: This includes maintaining the security of operating systems, applications, and firmware in a timely manner. Consider using a centralized patch management system; use a risk-based assessment strategy to drive your patch management program.
Test your incident response plan: There's nothing that shows the gaps in plans more than testing them. Run through some core questions and use those to build an incident response plan: Are you able to sustain business operations without access to certain systems? For how long? Would you turn off your manufacturing operations if business systems such as billing were offline?
Check your security team's work: Use a 3rd party pen tester to test the security of your systems and your ability to defend against a sophisticated attack. Many ransomware criminals are aggressive and sophisticated and will find the equivalent of unlocked doors.
Segment your networks: There's been a recent shift in ransomware attacks – from stealing data to disrupting operations. It's critically important that your corporate business functions and manufacturing/production operations are separated and that you carefully filter and limit internet access to operational networks, identify links between these networks, and develop workarounds or manual controls to ensure ICS networks can be isolated and continue operating if your corporate network is compromised. Regularly test contingency plans such as manual controls so that safety-critical functions can be maintained during a cyber incident.
Train employees: Email remains the most vulnerable attack vector for organizations. Users should be trained on how to avoid and spot phishing emails.
Implement multi-factor authentication (MFA): External-facing assets that leverage single-factor authentication (SFA) are highly susceptible to brute-forcing attacks, password spraying, or unauthorized remote access using valid (stolen) credentials. Implementing MFA enhances security and adds an extra layer of protection.
Link(s):
https://blog.talosintelligence.com/kraken-ransomware-group/
Kraken is a Russian-speaking ransomware group that emerged in early 2025 from the remnants of the HelloKitty cartel, adopting the same double-extortion model and even reusing HelloKitty’s ransom note filename. The group conducts opportunistic big-game hunting attacks across multiple regions, including the U.S., U.K., Canada, Denmark, Panama, and Kuwait, with ransom demands reaching $1M in Bitcoin. In August 2025, Cisco Talos observed Kraken exploiting exposed SMB vulnerabilities for initial access, followed by credential harvesting, re-entry via RDP using stolen admin accounts, and establishing persistence with Cloudflared reverse tunnels. The actor used SSHFS to explore the environment and exfiltrate data before deploying the Kraken ransomware binary and moving laterally via RDP to additional systems.
Kraken operates as a cross-platform ransomware family, with dedicated encryptors for Windows, Linux, and VMware ESXi. It supports extensive command-line options, full or partial encryption, SQL and network share targeting, and capabilities specifically designed for enterprise environments. A notable feature is Kraken’s encryption benchmarking, where the malware measures system throughput to choose between full or partial encryption, an uncommon characteristic in ransomware operations. The Windows encryptor includes anti-reinfection logic, WoW64 redirection manipulation, privilege escalation, SQL/Hyper-V/drive encryption modules, and extensive anti-analysis measures such as control-flow obfuscation, sleep delays, suppression of error dialogs, VSS deletion, and service disabling.
Security Officer Comments:
The Linux/ESXi encryptor includes platform detection (ESXi, Nutanix, Synology, Ubuntu), forceful VM termination, daemonized execution, control-flow obfuscation, and a multi-stage cleanup process using a self-deleting bash script to erase forensic traces. Kraken’s encrypted files use the .zpsc extension and victims receive a ransom note titled readme_you_ws_hacked.txt. The group also launched a new cybercrime forum, The Last Haven Board, from its leak site, with purported support from HelloKitty and WeaCorp, reinforcing links between these actors and signaling an attempt to expand its underground influence. Kraken demonstrates a level of maturity and enterprise-aware tradecraft that strongly aligns with its suspected lineage from HelloKitty. Its operational behavior, particularly the use of Cloudflared tunnels, SSHFS-based exfiltration, VM termination, and multi-platform encryptors, shows it is built for full intrusion operations rather than simple smash-and-grab ransomware deployment.
Suggested Corrections:
Backup your data, system images, and configurations, regularly test them, and keep the backups offline: Ensure that backups are regularly tested and that they are not connected to the business network, as many ransomware variants try to find and encrypt or delete accessible backups. Maintaining current backups offline is critical because if your network data is encrypted with ransomware, your organization can restore systems.
Update and patch systems promptly: This includes maintaining the security of operating systems, applications, and firmware in a timely manner. Consider using a centralized patch management system; use a risk-based assessment strategy to drive your patch management program.
Test your incident response plan: There's nothing that shows the gaps in plans more than testing them. Run through some core questions and use those to build an incident response plan: Are you able to sustain business operations without access to certain systems? For how long? Would you turn off your manufacturing operations if business systems such as billing were offline?
Check your security team's work: Use a 3rd party pen tester to test the security of your systems and your ability to defend against a sophisticated attack. Many ransomware criminals are aggressive and sophisticated and will find the equivalent of unlocked doors.
Segment your networks: There's been a recent shift in ransomware attacks – from stealing data to disrupting operations. It's critically important that your corporate business functions and manufacturing/production operations are separated and that you carefully filter and limit internet access to operational networks, identify links between these networks, and develop workarounds or manual controls to ensure ICS networks can be isolated and continue operating if your corporate network is compromised. Regularly test contingency plans such as manual controls so that safety-critical functions can be maintained during a cyber incident.
Train employees: Email remains the most vulnerable attack vector for organizations. Users should be trained on how to avoid and spot phishing emails.
Implement multi-factor authentication (MFA): External-facing assets that leverage single-factor authentication (SFA) are highly susceptible to brute-forcing attacks, password spraying, or unauthorized remote access using valid (stolen) credentials. Implementing MFA enhances security and adds an extra layer of protection.
Link(s):
https://blog.talosintelligence.com/kraken-ransomware-group/