Ransomware Research

Netwalker Ransomware

Netwalker is a malicious ransomware strain that encrypts victim files and demands ransom payment for decryption. First observed in the wild on September 1, 2019, this ransomware has been actively targeting systems worldwide. Security researchers also track this malware under the aliases: Mailto, Koko, NetWalker Doxware.

Quick facts

Ransomware Family
Netwalker
First Seen
September 1, 2019
Known Aliases
MailtoKokoNetWalker Doxware

How Netwalker ransomware works

File encryption patterns

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

Extensions added after encryption
./\.[A-F0-9a-f]{4,6}$/

Ransom note and payment demands

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

file/^[A-F0-9a-f]{5,6}-Readme\.txt$/
notes/5E728-Readme.txt
Location: EveryFolder

Technical indicators

Associated executable files

The following executable files are associated with Netwalker ransomware:

About this analysis

This Netwalker 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 Netwalker.

Last updated: December 30, 2025

Detection coverage

Elastio detects Netwalker inside your data and backups.

The Hunt Engine uses Deep File Inspection to identify Netwalker 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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