Ransomware Research

Mermaid Ransomware

Mermaid is a malicious ransomware strain that encrypts victim files and demands ransom payment for decryption. First observed in the wild on December 1, 2019, this ransomware has been actively targeting systems worldwide. Security researchers also track this malware under the aliases: Deniz Kizi, DenizKizi.

Quick facts

Ransomware Family
Mermaid
First Seen
December 1, 2019
Known Aliases
Deniz KiziDenizKizi

How Mermaid ransomware works

File encryption patterns

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

Extensions added after encryption
.Deniz_Kızı.Deniz_Kizi

Ransom note and payment demands

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

filePlease Read Me!!!.hta
notes/Please Read Me!!!.hta
Location: UserFolders
fileLütfen Beni Oku!!!.log
notes/Lütfen Beni Oku!!!.log
Location: UserFolders, RootDirectory
filePlease Read ME!!!.log
notes/Please Read ME!!!.log
Location: UserFolders
fileBeni_Oku!!!.hta
notes/Beni_Oku!!!.hta
Location: UserFolders

Technical indicators

Associated executable files

The following executable files are associated with Mermaid ransomware:

About this analysis

This Mermaid 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 Mermaid.

Last updated: December 30, 2025

Detection coverage

Elastio detects Mermaid inside your data and backups.

The Hunt Engine uses Deep File Inspection to identify Mermaid 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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What is Mermaid Ransomware? | Elastio