Onion Ransomware / CTB-Locker (also known as CTB-Locker, Onion, Critroni) is a malware active since 2014. TOR-based ransomware. Key characteristics include: TOR-based C2, curve25519 encryption, multilingual, one of first TOR ransomware.
Overview & Background
TOR-based ransomware. First identified in 2014, this threat is attributed to eCrime.
Threat Assessment
Onion Ransomware remains an active threat. Organizations should implement detection rules and monitor for indicators associated with this malware.
- Category: Malware
- Active since: 2014
- Attribution: eCrime
- Also known as: CTB-Locker, Onion, Critroni
Technical Analysis
Onion Ransomware employs the following capabilities and techniques:
- Tor-Based C2: Core functionality
- Curve25519 Encryption: Core functionality
- Multilingual: Core functionality
- One Of First Tor Ransomware: Core functionality
MITRE ATT&CK Mapping
| Tactic | Technique | Usage |
|---|---|---|
| Initial Access | T1566.001 Phishing Attachment | Common delivery vector |
| Execution | T1204.002 Malicious File | User-triggered execution |
| Persistence | T1547.001 Registry Run Keys | Autostart persistence |
| Defense Evasion | T1027 Obfuscated Files | Payload obfuscation |
| C2 | T1071.001 Web Protocols | HTTP/HTTPS C2 |
Detection & Defense
- Endpoint detection: Deploy behavioral detection rules for Onion Ransomware indicators
- Network monitoring: Monitor for C2 traffic patterns and anomalous connections
- Threat intelligence: Track Onion Ransomware IOCs and campaign updates
- Security awareness: Train users to recognize phishing and social engineering
- Patch management: Keep systems updated to prevent exploitation
Defend Against Onion Ransomware
Mjolnir Security provides detection and response capabilities against Onion Ransomware and similar threats.
Threat DetectionIncident ResponseThreat HuntingMDR ServicesThreat Intelligence
- Proactive Threat Hunting Hunt for Onion Ransomware indicators and TTPs within your environment.
- Threat Intelligence Monitor Onion Ransomware campaigns and infrastructure changes.
- 24/7 Incident Response Rapid containment and forensic investigation. Call +1 833 403 5875.
Written by: Mjolnir Security | Published: April 9, 2025
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