CVE-2024-56828
📋 TL;DR
This CVE describes a file upload vulnerability in ChestnutCMS that allows attackers to upload arbitrary files by bypassing extension validation. Attackers can upload malicious files like HTML, JavaScript, or server-side scripts to achieve remote code execution or cross-site scripting. All users running ChestnutCMS versions up to 1.5.0 are affected.
💻 Affected Systems
- ChestnutCMS
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or ransomware deployment
Likely Case
Webshell upload enabling persistent backdoor access and data exfiltration
If Mitigated
Limited impact with proper file extension validation and content-type checking
🎯 Exploit Status
Exploitation requires only base64 encoding of malicious payload and HTTP request to vulnerable endpoint
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available
Restart Required: No
Instructions:
No official patch available. Monitor the Gitee repository for updates and apply when released.
🔧 Temporary Workarounds
Disable vulnerable endpoint
allBlock access to the /api/member/avatar endpoint via web server configuration or firewall rules
# Apache: RewriteRule ^/api/member/avatar - [F]
# Nginx: location ~ ^/api/member/avatar { deny all; }
Implement WAF rules
allAdd web application firewall rules to block base64-encoded file uploads to the avatar endpoint
# ModSecurity rule: SecRule REQUEST_URI "@streq /api/member/avatar" "id:1001,phase:2,deny,status:403"
🧯 If You Can't Patch
- Implement strict file extension validation on the server-side before writing files
- Add authentication and authorization checks to the avatar upload endpoint
🔍 How to Verify
Check if Vulnerable:
Test by sending a base64-encoded file with malicious extension to /api/member/avatar endpointCheck Version:
Check ChestnutCMS version in admin panel or configuration filesVerify Fix Applied:
Verify that file extension validation is implemented and only allowed image types are accepted📡 Detection & Monitoring
Log Indicators:
- Unusual file uploads to /api/member/avatar
- Files with non-image extensions being written
- Base64 strings containing HTML/script content
Network Indicators:
- POST requests to /api/member/avatar with base64 payloads
- Unusual file upload patterns
SIEM Query:
source="web_server" AND uri="/api/member/avatar" AND request_body CONTAINS "base64"