Ransomware Research

Chaco Ransomware

Chaco is a malicious ransomware strain that encrypts victim files and demands ransom payment for decryption. First observed in the wild on June 1, 2025, this ransomware has been actively targeting systems worldwide.

Quick Facts

Ransomware Family
Chaco
First Seen
June 1, 2025

How Chaco Ransomware Works

File Encryption Patterns

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

File extensions added after encryption:

./\.[0-9a-z]{4}$/

Ransom Note and Payment Demands

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

filereadmebuster.txt

Ransom message:

notes/readmebuster.txt

Note locations:

UserFolders
screenshot

Ransom message:

notes/nuyww298c.png

Note locations:

Desktop

Technical Indicators

Associated Executable Files

The following executable files are associated with Chaco ransomware:

  • ChacoRansomware.exe
  • System.exe

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About This Analysis

This Chaco 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 Chaco.

Last updated: October 30, 2025

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