Thor

Ragnarök: F6 Investigates VantaCore Ransomware Attacks and Suspected Thor Rebrand

F6's Digital Forensics Laboratory has identified a new ransomware group called VantaCore that has struck at least seven Russian organizations with multimillion-dollar ransom demands. Researchers assess VantaCore as a rebrand of the previously known pro-Ukrainian Thor group, part of a broader consolidation among such actors in 2025–2026. The group abandoned LockBit 3 Black and Babuk in favor of its own VantaCore ransomware built on similar foundations, while deploying custom tools including VantaCoreLoader, VantaCoreRAT, and the SnowKiller BYOVD utility. VantaCore maintains a Tor-based data leak site launched no later than June 2026 and uses double and triple extortion tactics, selling or publicly releasing stolen data after encryption. Initial access relies on exposed RDP, VPN, public application vulnerabilities, and compromised partner credentials, followed by lateral movement via legitimate accounts and SMB/RDP. The group disables security products, clears logs, and destroys backups using Bootice before deploying its ChaCha20/X25519 ransomware via manual RDP sessions or automated loaders.

VantaCore Ransomware Group Targets Russian Businesses with Custom Toolkit and Triple Extortion

Security researchers at F6 have identified a new ransomware operation called VantaCore that is actively attacking small and medium-sized Russian companies. The group employs a custom set of tools including VantaCoreLoader, VantaCoreRAT, and its own encryption malware to conduct double and triple extortion campaigns. Initial access is gained through poorly secured RDP and VPN services, vulnerable public applications, and compromised partner accounts. Once inside the network, attackers move laterally using SMB and RDP with legitimate credentials, deploy Tactical RMM, and install their backdoor before disabling security products with an AV/EDR killer. Victims face data theft, backup destruction, and encryption, followed by threats to publish or sell stolen information if ransom demands in the millions of dollars are not met. F6 assesses that VantaCore may be a rebranded version of the previously known pro-Ukrainian group Thor, based on similar Tor negotiation chat design and a THOR rune icon on the leak site that appeared no later than June 7, 2026.