CVE-2020-21121
📋 TL;DR
CVE-2020-21121 is a critical SQL injection vulnerability in Pligg CMS that allows attackers to execute arbitrary SQL commands through the admin_update_module_widgets.php file. This affects all Pligg CMS 2.0.2 installations and can lead to complete system compromise. Attackers can exploit this to steal sensitive data, modify database contents, or gain administrative access.
💻 Affected Systems
- Pligg CMS
- Kliqqi CMS
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system takeover: attacker gains administrative privileges, exfiltrates all database data (including user credentials), installs backdoors, and potentially compromises the entire server.
Likely Case
Database compromise: attacker extracts sensitive information (user data, passwords, configuration), modifies content, or gains administrative access to the CMS.
If Mitigated
Limited impact due to proper input validation and parameterized queries preventing SQL injection execution.
🎯 Exploit Status
Exploitation requires admin access to reach the vulnerable endpoint; time-based SQL injection allows blind exploitation without direct output.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.0.3 or later
Vendor Advisory: https://github.com/Kliqqi-CMS/Kliqqi-CMS/issues/259
Restart Required: No
Instructions:
1. Backup your database and files. 2. Download the latest version from the official repository. 3. Replace vulnerable files with patched versions. 4. Verify the admin_update_module_widgets.php file uses parameterized queries.
🔧 Temporary Workarounds
Input Validation Filter
allAdd input validation to sanitize the $recordIDValue parameter before processing
Modify admin_update_module_widgets.php to validate $recordIDValue as integer using is_numeric() or filter_var()
Access Restriction
linuxRestrict access to admin_update_module_widgets.php file
Add .htaccess rules to restrict IP access: Order deny,allow
Deny from all
Allow from 192.168.1.0/24
🧯 If You Can't Patch
- Implement web application firewall (WAF) rules to block SQL injection patterns targeting the vulnerable parameter
- Disable or remove the admin_update_module_widgets.php file if functionality is not required
🔍 How to Verify
Check if Vulnerable:
Check if admin_update_module_widgets.php exists and contains unsanitized $recordIDValue parameter usage in SQL queriesCheck Version:
Check CMS version in configuration files or admin panel; look for version 2.0.2Verify Fix Applied:
Verify the file uses parameterized queries (prepared statements) or proper input validation for $recordIDValue📡 Detection & Monitoring
Log Indicators:
- Unusual SQL queries in database logs
- Multiple failed login attempts followed by admin_update_module_widgets.php access
- Long response times from admin_update_module_widgets.php (time-based SQLi indicator)
Network Indicators:
- POST requests to admin_update_module_widgets.php with suspicious parameter values
- Unusual database connection patterns from web server
SIEM Query:
source="web_logs" AND uri="/admin_update_module_widgets.php" AND (param="recordIDValue" AND value MATCH "[';]|UNION|SELECT|SLEEP")