Ransomware Research

S4b Ransomware

S4b is a malicious ransomware strain that encrypts victim files and demands ransom payment for decryption. First observed in the wild on September 1, 2023, this ransomware has been actively targeting systems worldwide.

Quick Facts

Ransomware Family
S4b
First Seen
September 1, 2023

How S4b Ransomware Works

Targeted Files

Full extension -> .id[C63F241F-3449].[submarine@cyberfear.com].s4b

File Encryption Patterns

S4b modifies encrypted files using specific patterns to mark them as encrypted:

File extensions added after encryption:

..s4b

Ransom Note and Payment Demands

After encrypting files, S4b displays ransom notes demanding payment for file recovery:

fileinfo.hta

Ransom message:

notes/info.hta

Note locations:

RootDiscsDesktop
fileinfo.txt

Ransom message:

notes/info.txt

Note locations:

RootDiscsDesktop

Technical Indicators

Associated Executable Files

The following executable files are associated with S4b ransomware:

  • Backup.exe

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About This Analysis

This S4b 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 S4b.

Last updated: July 30, 2025

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