Ransomware Research

OhNo! Ransomware

OhNo! is a malicious ransomware strain that encrypts victim files and demands ransom payment for decryption. First observed in the wild on August 1, 2017, this ransomware has been actively targeting systems worldwide.

Quick Facts

Ransomware Family
OhNo!
First Seen
August 1, 2017

How OhNo! Ransomware Works

File Encryption Patterns

OhNo! modifies encrypted files using specific patterns to mark them as encrypted:

File extensions added after encryption:

..OhNo!

Ransom Note and Payment Demands

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

message

Ransom message:

notes/note.txt

Note locations:

OnceOnCompletion
screenshot

Ransom message:

notes/wallpaper.jpg

Note locations:

Desktop

Technical Indicators

Associated Executable Files

The following executable files are associated with OhNo! ransomware:

  • Google Chrome
  • Defender.exe
  • Google Chrome.exe
  • ChromeBTCExtension.exe
  • Malware (38).exe

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About This Analysis

This OhNo! 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 OhNo!.

Last updated: July 30, 2025

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