CVE-2021-40965
📋 TL;DR
This CSRF vulnerability in TinyFileManager allows attackers to trick authenticated administrators into executing malicious requests, leading to arbitrary file uploads and remote code execution. All versions up to 2.4.6 are affected when an administrator visits a malicious URL while logged in.
💻 Affected Systems
- TinyFileManager
📦 What is this software?
Tiny File Manager by Prasathmani
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise through remote code execution, allowing attackers to install malware, steal data, or pivot to other systems.
Likely Case
Unauthorized file upload leading to webshell deployment and subsequent command execution on the server.
If Mitigated
Attack fails due to CSRF protections or administrator not being logged in during malicious URL visit.
🎯 Exploit Status
Exploit requires social engineering to get administrator to click malicious link while authenticated.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.4.7 and later
Vendor Advisory: https://github.com/prasathmani/tinyfilemanager
Restart Required: No
Instructions:
1. Backup current installation. 2. Download latest version from GitHub. 3. Replace files with patched version. 4. Verify functionality.
🔧 Temporary Workarounds
Implement CSRF Tokens
allAdd CSRF protection to file upload and command execution endpoints
Manual code modification required - implement anti-CSRF tokens in forms
Restrict Administrator Access
allLimit administrator access to trusted networks only
Configure firewall rules to restrict TinyFileManager admin interface
🧯 If You Can't Patch
- Implement web application firewall with CSRF protection rules
- Require re-authentication for sensitive actions like file uploads
🔍 How to Verify
Check if Vulnerable:
Check TinyFileManager version in config.php or about pageCheck Version:
grep -i 'version' config.php || check web interface about pageVerify Fix Applied:
Verify version is 2.4.7 or higher and test CSRF protection on upload forms📡 Detection & Monitoring
Log Indicators:
- Unexpected file uploads via POST requests
- Command execution attempts in web server logs
Network Indicators:
- CSRF attack patterns with malicious referrer headers
- Unexpected file uploads to TinyFileManager
SIEM Query:
source="web_logs" AND (uri="/tinyfilemanager/upload.php" OR uri CONTAINS "tinyfilemanager") AND method="POST" AND NOT user_agent="browser"