Ransomware Research

CryptoJoker Ransomware

CryptoJoker is a malicious ransomware strain that encrypts victim files and demands ransom payment for decryption. First observed in the wild on December 1, 2015, this ransomware has been actively targeting systems worldwide.

Quick facts

Ransomware Family
CryptoJoker
First Seen
December 1, 2015

How CryptoJoker ransomware works

File encryption patterns

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

Extensions added after encryption
.crjoker

Ransom note and payment demands

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

fileDECRYPT FILES.txt
notes/DECRYPT FILES.txt
Location: Desktop
fileGET MY FILES.txt
notes/GET MY FILES.txt
Location: Desktop
fileREAD.txt
notes/READ.txt
Location: Desktop
filereadme.txt
notes/readme.txt
Location: Desktop
fileREADME!!!.txt
notes/README!!!.txt
Location: Desktop
fileREAD NOW.txt
notes/READ NOW.txt
Location: Desktop
fileREAD NOW.txt
notes/READ NOW.txt
Location: Desktop
fileread this file.txt
notes/read this file.txt
Location: Desktop
fileПРОЧТИ.txt
notes/ПРОЧТИ.txt
Location: Desktop
fileРАСШИФРОВАТЬ ФАЙЛЫ.txt
notes/РАСШИФРОВАТЬ ФАЙЛЫ.txt
Location: Desktop
message
notes/note.txt
Location: Login

Technical indicators

Associated executable files

The following executable files are associated with CryptoJoker ransomware:

About this analysis

This CryptoJoker 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 CryptoJoker.

Last updated: December 30, 2025

Detection coverage

Elastio detects CryptoJoker inside your data and backups.

The Hunt Engine uses Deep File Inspection to identify CryptoJoker 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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