Ransomware Research

Katyusha Ransomware

Katyusha is a malicious ransomware strain that encrypts victim files and demands ransom payment for decryption. First observed in the wild on October 1, 2018, this ransomware has been actively targeting systems worldwide. Security researchers also track this malware under the aliases: Sysfrog.

Quick Facts

Ransomware Family
Katyusha
First Seen
October 1, 2018
Known Aliases
Sysfrog

How Katyusha Ransomware Works

File Encryption Patterns

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

File extensions added after encryption:

..katyusha..sysfrog

Prefixes added to encrypted files:

[sysfrog@protonmail.com]

Ransom Note and Payment Demands

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

file_how_to_decrypt_you_files.txt

Ransom message:

notes/_how_to_decrypt_you_files.txt

Note locations:

ProgramData
filehow_to_decrypt.txt

Ransom message:

notes/how_to_decrypt.txt

Note locations:

ProgramDataRootDiscs

Technical Indicators

Associated Executable Files

The following executable files are associated with Katyusha ransomware:

  • katyusha
  • katyusha.exe
  • KatyushaRansomware.bin
  • Trojan.Ransom.Katyusha.exe
  • KatyushaRansomware.exe
  • Ransomware Katyusha.exe
  • 604.json
  • 2018-10-14 Katyusha.exe
  • Katyusha.exe
  • myfile.exe
  • out
  • drprov.dll
  • Katyusha.ransom.exe

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About This Analysis

This Katyusha 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 Katyusha.

Last updated: July 30, 2025

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