Ransomware Research

Ryuk Ransomware

Ryuk is a malicious ransomware strain that encrypts victim files and demands ransom payment for decryption. First observed in the wild on August 1, 2018, this ransomware has been actively targeting systems worldwide. Security researchers also track this malware under the aliases: Ryuk 2.0.

Quick facts

Ransomware Family
Ryuk
First Seen
August 1, 2018
Known Aliases
Ryuk 2.0

How Ryuk ransomware works

File encryption patterns

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

Extensions added after encryption
.rcrypted.RYK

Ransom note and payment demands

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

fileREADME.PLEASE.txt
notes/README.PLEASE.txt
fileRyukReadMe.txt
notes/RyukReadMe.txt
Location: EveryFolder
fileReadMe.txt
notes/ReadMe.txt
fileRyukReadMe.html
notes/RyukReadMe.html
Location: EveryFolder

Technical indicators

Associated executable files

The following executable files are associated with Ryuk ransomware:

About this analysis

This Ryuk ransomware analysis is part of Elastio's comprehensive ransomware detection database. Elastio provides advanced ransomware protection and recovery, helping organizations defend against and recover from ransomware attacks like Ryuk.

Last updated: December 30, 2025

Detection coverage

Elastio detects Ryuk inside your data and backups.

The Hunt Engine uses Deep File Inspection to identify Ryuk across live data, replicated data, and backups. If this family is in your environment, Elastio finds it before encryption completes. Run a scan against your recovery points to confirm.

See How the Hunt Engine WorksRequest a Demo

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