CVE-2021-25200
📋 TL;DR
This CVE describes an arbitrary file upload vulnerability in SourceCodester Learning Management System v1.0, allowing attackers to upload malicious files to execute arbitrary code on the server. It affects users running this specific version of the software, potentially leading to full system compromise.
💻 Affected Systems
- SourceCodester Learning Management System
📦 What is this software?
Learning Management System by Learning Management System Project
⚠️ Risk & Real-World Impact
Worst Case
Full remote code execution leading to complete system takeover, data theft, or deployment of ransomware.
Likely Case
Attackers upload web shells to gain persistent access, steal sensitive data, or pivot to other systems.
If Mitigated
With proper file upload validation and server hardening, impact is limited to denial-of-service or minor data exposure.
🎯 Exploit Status
Exploitation involves uploading a malicious file via the student avatar feature; public references suggest it's straightforward.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: No
Instructions:
No official patch; consider upgrading to a newer version if available, or apply workarounds.
🔧 Temporary Workarounds
Restrict File Uploads
allImplement server-side validation to allow only specific file types (e.g., images) and sanitize filenames.
Modify student_avatar.php to include file type and extension checks.
Disable Vulnerable Endpoint
allTemporarily disable or restrict access to the student_avatar.php file.
Use web server config (e.g., .htaccess for Apache) to block access to /lms/student_avatar.php.
🧯 If You Can't Patch
- Implement network segmentation to isolate the system and limit access.
- Deploy a web application firewall (WAF) with rules to block malicious file uploads.
🔍 How to Verify
Check if Vulnerable:
Attempt to upload a non-image file (e.g., .php) to the student avatar upload feature and check if it's accepted.Check Version:
Check the software version in the system's admin panel or configuration files.Verify Fix Applied:
After applying workarounds, test that only allowed file types are accepted and malicious uploads are blocked.📡 Detection & Monitoring
Log Indicators:
- Unusual file uploads to student_avatar.php, especially with non-image extensions.
Network Indicators:
- HTTP POST requests to /lms/student_avatar.php with suspicious file content.
SIEM Query:
source="web_logs" AND uri="/lms/student_avatar.php" AND method="POST" AND file_extension NOT IN ("jpg", "png", "gif")