Ransomware Research

Zyklon Ransomware

Zyklon is a malicious ransomware strain that encrypts victim files and demands ransom payment for decryption. First observed in the wild on May 1, 2016, this ransomware has been actively targeting systems worldwide.

Quick Facts

Ransomware Family
Zyklon
First Seen
May 1, 2016

How Zyklon Ransomware Works

File Encryption Patterns

Zyklon modifies encrypted files using specific patterns to mark them as encrypted:

File extensions added after encryption:

..zyklon..srpx

Ransom Note and Payment Demands

After encrypting files, Zyklon displays ransom notes demanding payment for file recovery:

file/\bREADME_TO_RESTORE_FILES_[A-Za-z0-9]{3}\.html\b/

Ransom message:

notes/README_TO_RESTORE_FILES_o6W.html

Note locations:

UserFoldersRootDiscs
file/\bREADME_TO_RESTORE_FILES_[A-Za-z0-9]{3}\.txt\b/

Ransom message:

notes/README_TO_RESTORE_FILES_o6W.txt

Note locations:

UserFoldersRootDiscs

Technical Indicators

Associated Executable Files

The following executable files are associated with Zyklon ransomware:

  • Octopus
  • 6612683490_2604543229_download.zp.exe
  • Serpent.exe
  • urlref_http185.183.99.24update.zp
  • update.zp

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About This Analysis

This Zyklon 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 Zyklon.

Last updated: October 30, 2025

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