Jamper Ransomware
Jamper is a malicious ransomware strain that encrypts victim files and demands ransom payment for decryption. First observed in the wild on March 1, 2019, this ransomware has been actively targeting systems worldwide. Security researchers also track this malware under the aliases: Jumper.
Quick facts
How Jamper ransomware works
File encryption patterns
Jamper modifies encrypted files using specific patterns to mark them as encrypted:
Ransom note and payment demands
After encrypting files, Jamper displays ransom notes demanding payment for file recovery:
notes/---README---.TXT
Technical indicators
Associated executable files
The following executable files are associated with Jamper ransomware:
- DEFENDER.EXE
- defender.exe
- defender.exe.VIRUS
About this analysis
This Jamper 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 Jamper.
Last updated: December 30, 2025
Elastio detects Jamper inside your data and backups.
The Hunt Engine uses Deep File Inspection to identify Jamper 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.
Recent ransomware
Explore other threats in our database