CVE-2023-1789
📋 TL;DR
CVE-2023-1789 is an improper input validation vulnerability in Firefly III personal finance software that allows attackers to execute arbitrary code on affected systems. This affects all users running Firefly III versions prior to 6.0.0. The vulnerability stems from insufficient validation of user-supplied input in the application.
💻 Affected Systems
- Firefly III
📦 What is this software?
Firefly Iii by Firefly Iii
Firefly Iii by Firefly Iii
Firefly Iii by Firefly Iii
Firefly Iii by Firefly Iii
Firefly Iii by Firefly Iii
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with remote code execution, allowing attackers to gain full control over the server, access sensitive financial data, and potentially pivot to other systems.
Likely Case
Remote code execution leading to data theft, unauthorized financial transactions, and installation of backdoors or malware on the affected system.
If Mitigated
Limited impact with proper network segmentation, application firewalls, and least-privilege configurations, potentially reducing to denial of service or information disclosure.
🎯 Exploit Status
The vulnerability is publicly documented with proof-of-concept available, making exploitation straightforward for attackers with basic skills.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 6.0.0 and later
Vendor Advisory: https://github.com/firefly-iii/firefly-iii/commit/6b05c0fbd3e8c40ae9b24dc2698821786fccf0c5
Restart Required: Yes
Instructions:
1. Backup your Firefly III database and configuration. 2. Update to Firefly III version 6.0.0 or later using your package manager or manual installation. 3. Restart the web server and application services. 4. Verify the update was successful by checking the version.
🔧 Temporary Workarounds
Input Validation Filter
allImplement custom input validation middleware to sanitize all user inputs before processing
Requires custom code implementation - no single command
Web Application Firewall
allDeploy a WAF with rules to block malicious input patterns targeting Firefly III
Depends on specific WAF solution
🧯 If You Can't Patch
- Isolate the Firefly III instance behind a reverse proxy with strict input validation
- Implement network segmentation to limit access to only trusted users and networks
🔍 How to Verify
Check if Vulnerable:
Check the Firefly III version in the application settings or via the web interface. If version is below 6.0.0, the system is vulnerable.Check Version:
Check the web interface at /about or examine the application configuration files for version information.Verify Fix Applied:
After updating, verify the version shows 6.0.0 or higher in the application settings. Test input validation by attempting to submit malformed data that should be rejected.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests with malformed parameters
- Error logs showing input validation failures
- Unexpected process executions from web server context
Network Indicators:
- Unusual outbound connections from the Firefly III server
- Suspicious payloads in HTTP requests to Firefly III endpoints
SIEM Query:
source="firefly-iii" AND (http_method="POST" AND (url_path="*vulnerable_endpoint*" OR http_user_agent="*malicious*"))🔗 References
- https://github.com/firefly-iii/firefly-iii/commit/6b05c0fbd3e8c40ae9b24dc2698821786fccf0c5
- https://huntr.dev/bounties/2c3489f7-6b84-48f8-9368-9cea67cf373d
- https://github.com/firefly-iii/firefly-iii/commit/6b05c0fbd3e8c40ae9b24dc2698821786fccf0c5
- https://huntr.dev/bounties/2c3489f7-6b84-48f8-9368-9cea67cf373d
