Lost_Files Ransomware
Lost_Files is a malicious ransomware strain that encrypts victim files and demands ransom payment for decryption. First observed in the wild on September 1, 2019, this ransomware has been actively targeting systems worldwide.
Quick facts
How Lost_Files ransomware works
File encryption patterns
Lost_Files modifies encrypted files using specific patterns to mark them as encrypted:
Ransom note and payment demands
After encrypting files, Lost_Files displays ransom notes demanding payment for file recovery:
notes/Ransomware Lost Files Message.txt
notes/note.txt
Technical indicators
Associated executable files
The following executable files are associated with Lost_Files ransomware:
- WSS.zip
- tmp.download
- B3B4JZUH.exe
- Lost_Files.exe
- wss.exe
- Windows Security Scanner.exe
- SecurityUpdater.exe.exe
- B1HFZL.exe
About this analysis
This Lost_Files 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 Lost_Files.
Last updated: December 30, 2025
Elastio detects Lost_Files inside your data and backups.
The Hunt Engine uses Deep File Inspection to identify Lost_Files 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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