Ransomware Research

Sigrun Ransomware

Sigrun is a malicious ransomware strain that encrypts victim files and demands ransom payment for decryption. First observed in the wild on May 1, 2018, this ransomware has been actively targeting systems worldwide.

Quick Facts

Ransomware Family
Sigrun
First Seen
May 1, 2018

How Sigrun Ransomware Works

File Encryption Patterns

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

File extensions added after encryption:

..sigrun

Ransom Note and Payment Demands

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

fileRESTORE-SIGRUN.txt

Ransom message:

notes/RESTORE-SIGRUN.txt

Note locations:

EveryFolder
fileRESTORE-SIGRUN.html

Ransom message:

notes/RESTORE-SIGRUN.html

Note locations:

EveryFolder

Technical Indicators

Associated Executable Files

The following executable files are associated with Sigrun ransomware:

  • 5.exe
  • sigrun.exe

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About This Analysis

This Sigrun 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 Sigrun.

Last updated: October 30, 2025

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