Kyber ransomware is not just post-quantum name-dropping

A detailed technical analysis confirms that Kyber ransomware implements genuine hybrid post-quantum cryptography rather than mere branding. The Rust-based Windows variant encrypts files using AES-256-CTR with Kyber1024 and X25519 for key protection, appending a fixed 0x744-byte trailer containing encrypted metadata. Instrumented analysis validated the cryptographic implementation through fixture decryption but found no practical recovery path from the sample alone. The encryptor targets multiple file types, deploys standard recovery-inhibition techniques, and marks encrypted files with a .#~~~ extension. A separate ESXi variant was found to use different cryptography despite similar branding. As of April 2026, one victim was publicly listed: a large American defense contractor and IT services provider.

• Dissection of Operation FlashHole, a complex attack by LazarusMalware2026-10-21
• Kyber Ransomware Double Trouble: Windows and ESXi Attacks ExplainedMalware2026-04-22
• Leveling Up with NightSpire RansomwareMalware2026-04-08
• Evasive Panda APT poisons DNS requests to deliver MgBotCampaign2025-12-24
• Signal Introduces Sparse Post-Quantum Ratchet (SPQR) to Strengthen Encryption Against Quantum AttacksAnalysis2025-10-05