Outsider Ransomware
Outsider is a malicious ransomware strain that encrypts victim files and demands ransom payment for decryption. First observed in the wild on December 1, 2018, this ransomware has been actively targeting systems worldwide.
Quick facts
How Outsider ransomware works
File encryption patterns
Outsider modifies encrypted files using specific patterns to mark them as encrypted:
Ransom note and payment demands
After encrypting files, Outsider displays ransom notes demanding payment for file recovery:
notes/HOW_TO_RESTORE_FILES.txt
notes/RESTORE_FILES.txt
notes/HOW_TO_RESTORE_YOUR_FILES.txt
notes/SECURITY-ISSUE-INFO.txt
notes/SGUARD-README.txt
notes/GUARDED-README.txt
notes/MAPO-Readme.txt
notes/Sivo-README.txt
notes/DANTE-INFO.txt
notes/MBIT-INFO.txt
notes/GOMER-README.txt
notes/ASSIST-README.txt
Technical indicators
Associated executable files
The following executable files are associated with Outsider ransomware:
- 900.exe
- MSIE.exe
- Trojan.Ransom.Mapo.exe
- Sivo.exe
- edab.exe
- assist.exe
- assist.bin
About this analysis
This Outsider 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 Outsider.
Last updated: December 30, 2025
Elastio detects Outsider inside your data and backups.
The Hunt Engine uses Deep File Inspection to identify Outsider 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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