Ransomware Research

CryptoFortress Ransomware

CryptoFortress is a malicious ransomware strain that encrypts victim files and demands ransom payment for decryption. First observed in the wild on March 1, 2016, this ransomware has been actively targeting systems worldwide.

Quick facts

Ransomware Family
CryptoFortress
First Seen
March 1, 2016

How CryptoFortress ransomware works

File encryption patterns

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

Extensions added after encryption
.frtrss

Ransom note and payment demands

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

fileREAD IF YOU WANT YOUR FILES BACK.html
notes/READ IF YOU WANT YOUR FILES BACK.html
Location: EveryFolder

About this analysis

This CryptoFortress 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 CryptoFortress.

Last updated: December 30, 2025

Detection coverage

Elastio detects CryptoFortress inside your data and backups.

The Hunt Engine uses Deep File Inspection to identify CryptoFortress 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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