CVE-2021-26822
📋 TL;DR
CVE-2021-26822 is a critical SQL injection vulnerability in Teachers Record Management System 1.0 that allows remote unauthenticated attackers to execute arbitrary SQL commands via the 'searchteacher' parameter. This can lead to database information disclosure, authentication bypass, and potentially remote code execution. All users running the vulnerable version are affected.
💻 Affected Systems
- Teachers Record Management System
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote unauthenticated attacker gains full database access, extracts sensitive information (credentials, personal data), executes arbitrary code on the server, and potentially compromises the entire system.
Likely Case
Attackers extract database contents including user credentials, modify data, and potentially escalate to remote code execution via database functions.
If Mitigated
With proper input validation and parameterized queries, the vulnerability is eliminated and no exploitation is possible.
🎯 Exploit Status
Exploit code is publicly available on Exploit-DB and GitHub. The vulnerability requires minimal technical skill to exploit.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: No official vendor advisory found
Restart Required: No
Instructions:
1. Download the vulnerable file search-teacher.php
2. Replace raw SQL queries with parameterized prepared statements
3. Implement proper input validation and sanitization
4. Test the fix thoroughly before deployment
🔧 Temporary Workarounds
Web Application Firewall (WAF)
allDeploy a WAF with SQL injection protection rules to block malicious requests
Input Validation Filter
allAdd server-side input validation to reject suspicious characters in searchteacher parameter
// PHP example: if(preg_match('/[\'"\;\-\#\*]/', $_POST['searchteacher'])) { die('Invalid input'); }
🧯 If You Can't Patch
- Isolate the system behind a firewall with strict access controls
- Implement network segmentation to limit potential lateral movement
🔍 How to Verify
Check if Vulnerable:
Test the search-teacher.php endpoint with SQL injection payloads like: searchteacher=' OR '1'='1Check Version:
Check the system documentation or about page for version informationVerify Fix Applied:
Attempt SQL injection tests and verify they are rejected or properly sanitized📡 Detection & Monitoring
Log Indicators:
- Unusual SQL error messages in logs
- Multiple failed login attempts after search queries
- Suspicious search parameters containing SQL keywords
Network Indicators:
- HTTP POST requests to search-teacher.php with SQL injection patterns
- Unusual database query patterns from web server
SIEM Query:
source="web_logs" AND uri="/search-teacher.php" AND (request_body CONTAINS "UNION" OR request_body CONTAINS "SELECT *" OR request_body CONTAINS "OR '1'='1'")🔗 References
- https://github.com/nu11secur1ty/CVE-mitre/tree/main/CVE-2021-26822
- https://phpgurukul.com/teachers-record-management-system-using-php-and-mysql/
- https://www.exploit-db.com/exploits/49562
- https://github.com/nu11secur1ty/CVE-mitre/tree/main/CVE-2021-26822
- https://phpgurukul.com/teachers-record-management-system-using-php-and-mysql/
- https://www.exploit-db.com/exploits/49562
