| name | rnsmwr-canary-files |
| description | Deploys and monitors ransomware canary files across critical directories using Python's watchdog library for real-time filesystem event detection. Places strategically named decoy files that mimic high-value targets (financial records, credentials, database exports) in locations ransomware typically enumerates first. Monitors for any read, modify, rename, or delete operations on canary files and triggers immediate alerts via email, Slack webhook, or syslog when interaction is detected, providing early warning before full encryption begins.
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| 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"] |
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
