Anubis Ransomware: Attack Chain Exposed
How cybercriminals exploit VPNs and RMM tools for large-scale breaches
1The Anubis Threat Landscape
Arctic Wolf Labs uncovered a series of sophisticated Anubis ransomware attacks in 2026 targeting enterprise networks. The cybercriminals employed stolen VPN credentials as their primary entry vector, exploiting the CitrixBleed 2 vulnerability. This initial access allowed them to bypass perimeter defenses undetected. The attacks demonstrate how ransomware groups continuously evolve their tactics to exploit common security weaknesses in corporate infrastructure.
2Stealthy Lateral Movement
After gaining initial access, attackers deployed Remote Monitoring and Management (RMM) tools to blend with legitimate IT activity. They used Remote Desktop Protocol (RDP) and PsExec for lateral movement across networks. This technique allowed them to maintain persistence while avoiding detection by security systems. The use of common administrative tools makes it challenging for defenders to distinguish between normal operations and malicious activity.
3Credential Harvesting Phase
The attackers systematically harvested credentials throughout the network, focusing on privileged accounts. They established tunnels and proxies to maintain access while preparing for the final ransomware deployment. This credential theft phase often goes undetected for weeks, giving attackers ample time to map the network and identify critical systems. The stolen credentials were later used to escalate privileges and disable security controls.
4Security Tool Tampering
Before deploying the ransomware payload, attackers deliberately tampered with security tools and backups. They disabled endpoint protection, deleted shadow copies, and encrypted backup servers. This systematic neutralization of defenses ensured maximum impact from the subsequent encryption phase. The research highlights how modern ransomware operators prioritize eliminating recovery options.
5The Encryption Event
The final stage involved simultaneous encryption of files across multiple systems using the Anubis ransomware. Attackers timed the deployment to maximize disruption during business hours. The ransomware employed strong encryption algorithms and appended unique extensions to compromised files. Arctic Wolf observed ransom demands ranging from $500,000 to $5 million depending on the victim's size and industry.
6Defender Disruption Points
The research identifies four critical points where defenders can disrupt the attack chain: initial VPN access, RMM tool deployment, credential theft activity, and security tool tampering. Early detection at any of these stages can prevent the final ransomware deployment. Arctic Wolf recommends enhanced monitoring of remote access tools and privileged account activity as key defensive measures.
7Industry-Wide Implications
These attacks highlight the growing sophistication of ransomware-as-a-service operations. The Anubis group's success stems from their ability to weaponize common IT tools and processes. Industries with distributed networks and remote workers are particularly vulnerable. The research underscores the need for behavioral detection capabilities beyond traditional signature-based defenses.
8Proactive Defense Strategy
Organizations must adopt a assume-breach mentality, focusing on detecting post-compromise activities. Arctic Wolf's findings emphasize the importance of monitoring for unusual RMM tool usage and anomalous credential access patterns. Regular credential rotation and strict RDP restrictions can significantly reduce attack surfaces. The research provides a blueprint for building resilience against evolving ransomware tactics.
Original article: CyberWire Daily — Anubis Ransomware: Attack Chain Exposed