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Kyber Ransomware Double Trouble: Windows and ESXi Attacks Explained
Kyber ransomware represents a significant threat through dual-platform deployment capabilities targeting VMware ESXi virtualization infrastructure and Windows file systems. During a March 2026 incident response engagement, two Kyber payloads were recovered from the same environment. The ESXi variant, written in C++, specifically targets VMware environments with datastore encryption, VM termination, and management interface defacement capabilities. The Windows variant, written in Rust, includes experimental Hyper-V targeting features. Both samples share campaign identifiers and Tor-based infrastructure, confirming coordinated cross-platform operations. Despite advertising post-quantum Kyber1024 encryption, the ESXi variant actually uses ChaCha8 with RSA-4096 key wrapping, while the Windows variant implements the claimed AES-256-CTR with Kyber1024 hybrid scheme. The ransomware includes anti-recovery measures, service termination, and effective encryption strategies designed to cause complete operational disr...
MITRE ATT&CK & Malware Families
Indicators of Compromise (5)
| TYPE | INDICATOR | DESCRIPTION | CREATED | |
|---|---|---|---|---|
| FileHash-MD5 | 18498b1ff111ee9d9a037c280f75b720 | — | 2026-04-22 | |
| FileHash-SHA1 | 0e9a47782e39741a2c161bf639252d33ad3a428a | — | 2026-04-22 | |
| FileHash-SHA256 | 45bff0df2c408b3f589aed984cc331b617021ecbea57171dac719b5f545f5e8d | — | 2026-04-22 | |
| FileHash-SHA256 | 4ed176edb75ae2114cda8cfb3f83ac2ecdc4476fa1ef30ad8c81a54c0a223a29 | — | 2026-04-22 | |
| FileHash-SHA256 | 6ccacb7567b6c0bd2ca8e68ff59d5ef21e8f47fc1af70d4d88a421f1fc5280fc | — | 2026-04-22 |