Ransomware Research

Surtr Ransomware

Surtr is a malicious ransomware strain that encrypts victim files and demands ransom payment for decryption. First observed in the wild on December 1, 2021, this ransomware has been actively targeting systems worldwide.

Quick Facts

Ransomware Family
Surtr
First Seen
December 1, 2021

How Surtr Ransomware Works

File Encryption Patterns

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

File extensions added after encryption:

..SURT..surtr

Ransom Note and Payment Demands

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

fileSURTR_README.hta

Ransom message:

notes/SURTR_README.hta

Note locations:

EveryFolder
fileSURTR_README.txt

Ransom message:

notes/SURTR_README.txt

Note locations:

EveryFolder

Technical Indicators

Associated Executable Files

The following executable files are associated with Surtr ransomware:

  • surtr.bin
  • Surtr.exe

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About This Analysis

This Surtr ransomware analysis is part of Elastio's comprehensive ransomware detection database. Elastio provides advanced ransomware protection and recovery solutions, helping organizations defend against and recover from ransomware attacks like Surtr.

Last updated: October 30, 2025

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