| name | deploying-ransomware-canary-files |
| description | Deploys and monitors ransomware canary files using Python's watchdog library, placing decoy files mimicking high-value targets (financial records, credentials, database exports) where ransomware enumerates first, and alerting via email, Slack, or syslog on any read/modify/rename/delete. Use for early-warning ransomware detection on file servers, NAS, or endpoints, or to supplement EDR where agents can't be deployed. |
| domain | cybersecurity |
| subdomain | ransomware-defense |
| tags | ["ransomware","canary-files","watchdog","detection","early-warning","deception","defense"] |
| version | 1.0.0 |
| author | mahipal |
| license | Apache-2.0 |
| nist_csf | ["PR.DS-11","RS.MA-01","RC.RP-01","PR.IR-01"] |
| mitre_attack | ["T1486","T1083","T1490","T1485"] |
| mitre_f3 | {"version":"1.1","tactics":["monetization"],"techniques":[{"id":"F1018","name":"Convert to Cryptocurrency","tactic":"monetization","source":"f3"},{"id":"F1017","name":"Conversion to Physical Monetary Instruments","tactic":"monetization","source":"f3"},{"id":"F1025.003","name":"Electronic Funds Transfer: Wire Transfer","tactic":"monetization","source":"f3"}]} |
Deploying Ransomware Canary Files
When to Use
- Deploying proactive ransomware detection on file servers, NAS devices, or endpoint systems
- Building an early-warning system that detects ransomware before it encrypts business-critical data
- Supplementing EDR solutions with lightweight canary file monitoring on systems where agents cannot be deployed
- Testing ransomware incident response procedures by simulating canary file triggers
- Monitoring shared drives, home directories, and backup volumes for unauthorized file operations
Do not use as a replacement for endpoint protection, backup strategy, or network segmentation. Canary files are a detection layer, not a prevention mechanism.
Prerequisites
- Python 3.8+ with pip
- watchdog library (pip install watchdog)
- Write access to directories where canary files will be placed
- SMTP server credentials or Slack webhook URL for alerting
- Administrative access for placing canaries in system directories
Workflow
Step 1: Generate Canary Files
Create decoy files with realistic names and content that attract ransomware scanners. Files should have names like Passwords.xlsx, Financial_Report_2026.docx, backup_credentials.csv and contain plausible-looking but fake data. Place them in directories ransomware typically targets first: user desktops, Documents folders, network share roots, and backup paths.
Step 2: Deploy Filesystem Monitor
Use Python's watchdog library with a custom FileSystemEventHandler that watches canary file paths. The handler triggers on on_modified, on_deleted, on_moved, and on_created events for canary files. Any legitimate user or process should never touch these files, so any interaction is a high-confidence indicator of ransomware or unauthorized access.
Step 3: Configure Alert Pipeline
Wire the filesystem monitor to multiple alert channels: email via SMTP, Slack webhook POST, syslog forwarding to SIEM, and local log file. Include the triggering event type, file path, timestamp, and process information (when available) in alert payloads.
Step 4: Validate and Test
Simulate ransomware behavior by programmatically modifying, renaming, and deleting canary files to verify the detection pipeline fires correctly. Measure time-to-alert and validate alert delivery across all configured channels.
Key Concepts
