Ransomware Research
Cthulhu Ransomware
Cthulhu is a malicious ransomware strain that encrypts victim files and demands ransom payment for decryption. First observed in the wild on July 1, 2023, this ransomware has been actively targeting systems worldwide.
Quick Facts
- Ransomware Family
- Cthulhu
- First Seen
- July 1, 2023
How Cthulhu Ransomware Works
Targeted Files
https://app.any.run/tasks/72d01246-b7d7-4c02-bd0b-fe81f99775ca/ https://tria.ge/230707-npz15sge49/ https://www.joesandbox.com/analysis/1269149/0/html Written in Rust Requirec C&C to send and receive information
File Encryption Patterns
Cthulhu modifies encrypted files using specific patterns to mark them as encrypted:
File extensions added after encryption:
..encRansom Note and Payment Demands
After encrypting files, Cthulhu displays ransom notes demanding payment for file recovery:
HELP_RECOVER_ALL_MY_FILES.txtRansom message:
notes/HELP_RECOVER_ALL_MY_FILES.txt
Note locations:
DesktopTechnical Indicators
Associated Executable Files
The following executable files are associated with Cthulhu ransomware:
rcrypt.execthlhu.exe
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About This Analysis
This Cthulhu ransomware analysis is part of Elastio's comprehensive ransomware detection database. Elastio provides advanced ransomware protection and recovery solutions, helping organizations defend against and recover from ransomware attacks like Cthulhu.
Last updated: July 30, 2025