Ransomware Research

Nemesis Ransomware

Nemesis is a malicious ransomware strain that encrypts victim files and demands ransom payment for decryption. First observed in the wild on May 1, 2017, this ransomware has been actively targeting systems worldwide. Security researchers also track this malware under the aliases: Nemesis NextGen.

Quick facts

Ransomware Family
Nemesis
First Seen
May 1, 2017
Known Aliases
Nemesis NextGen

How Nemesis ransomware works

File encryption patterns

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

Extensions added after encryption
./\.[a-z0-9]{4,5}$/.YOUR_LAST_CHANCE.WECANHELP.nemesis.t5019.aax55

Ransom note and payment demands

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

file### DECRYPT MY FILES ###.html
file### DECRYPT MY FILES ###.txt
notes/### DECRYPT MY FILES ###.txt
Location: EveryFolder
file_RESTORE FILES_.txt
notes/_RESTORE FILES_.txt
Location: EveryFolder

Technical indicators

Associated executable files

The following executable files are associated with Nemesis ransomware:

About this analysis

This Nemesis 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 Nemesis.

Last updated: December 30, 2025

Detection coverage

Elastio detects Nemesis inside your data and backups.

The Hunt Engine uses Deep File Inspection to identify Nemesis 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.

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What is Nemesis Ransomware? | Elastio