CVE-2021-33473
📋 TL;DR
CVE-2021-33473 is an argument injection vulnerability in the Dragonfly Ruby Gem v1.3.0 that allows attackers to read and write arbitrary files when the verify_url option is disabled. This can lead to unauthorized access, data theft, or system compromise. Users of Dragonfly Ruby Gem v1.3.0 with verify_url disabled are affected.
💻 Affected Systems
- Dragonfly Ruby Gem
📦 What is this software?
Dragonfly by Dragonfly Project
⚠️ Risk & Real-World Impact
Worst Case
Attackers could read sensitive files (e.g., configuration, credentials) or write malicious files to execute arbitrary code, potentially leading to full system compromise.
Likely Case
Attackers exploit crafted URLs to access or modify files on the server, resulting in data breaches or service disruption.
If Mitigated
With verify_url enabled or patched, the vulnerability is blocked, preventing file access and maintaining system integrity.
🎯 Exploit Status
Exploitation involves sending crafted URLs to the application; public references and commits indicate active awareness and potential exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after v1.3.0, specifically commit 25399297bb457f7fcf8e3f91e85945b255b111b5
Vendor Advisory: https://github.com/markevans/dragonfly/commit/25399297bb457f7fcf8e3f91e85945b255b111b5
Restart Required: Yes
Instructions:
1. Update the Dragonfly Ruby Gem to a version after v1.3.0. 2. Run 'bundle update dragonfly' in your Ruby application directory. 3. Restart the application server to apply changes.
🔧 Temporary Workarounds
Enable verify_url option
allSet the verify_url option to true in Dragonfly configuration to prevent argument injection via URLs.
In your Dragonfly config file, add or set: Dragonfly.app.configure { |c| c.verify_url = true }
🧯 If You Can't Patch
- Disable or restrict access to the vulnerable Dragonfly endpoints using network controls or application firewalls.
- Monitor logs for unusual URL patterns and implement strict input validation on URL parameters.
🔍 How to Verify
Check if Vulnerable:
Check if Dragonfly version is v1.3.0 and verify_url is disabled in configuration.Check Version:
Run 'bundle show dragonfly' or check Gemfile.lock for the Dragonfly version.Verify Fix Applied:
Confirm Dragonfly version is updated beyond v1.3.0 and verify_url is enabled or patched via commit check.📡 Detection & Monitoring
Log Indicators:
- Log entries showing crafted URLs with unusual parameters or file access attempts to sensitive paths.
Network Indicators:
- HTTP requests with suspicious URL patterns targeting Dragonfly endpoints, especially with file paths.
SIEM Query:
Example: search for HTTP requests where uri contains 'dragonfly' and (uri matches patterns like '../' or includes file extensions like .rb, .yml).🔗 References
- https://github.com/markevans/dragonfly/commit/25399297bb457f7fcf8e3f91e85945b255b111b5
- https://github.com/markevans/dragonfly/issues/513
- https://security.netapp.com/advisory/ntap-20220715-0004/
- https://github.com/markevans/dragonfly/commit/25399297bb457f7fcf8e3f91e85945b255b111b5
- https://github.com/markevans/dragonfly/issues/513
- https://security.netapp.com/advisory/ntap-20220715-0004/
