CVE-2020-37057: Online-Exam-System SQL Injection Flaw

CVE-2020-37057 Overview

Online-Exam-System 2015 contains a SQL injection vulnerability in the feedback module that allows attackers to manipulate database queries through the 'fid' parameter. Attackers can inject malicious SQL code into the 'fid' parameter to potentially extract, modify, or delete database information. This classic SQL injection flaw enables unauthorized database access and poses significant risks to data confidentiality and integrity.

Critical Impact

Unauthenticated attackers can exploit this SQL injection vulnerability to extract sensitive user data, modify exam records, or potentially compromise the entire database backend of Online-Exam-System deployments.

Affected Products

• Online-Exam-System 2015
• Online-Exam-System feedback module (fid parameter)
• Web applications using the vulnerable Online-Exam-System codebase

Discovery Timeline

• 2026-01-30 - CVE-2020-37057 published to NVD
• 2026-02-03 - Last updated in NVD database

Technical Details for CVE-2020-37057

Vulnerability Analysis

This vulnerability is classified as CWE-89 (Improper Neutralization of Special Elements used in an SQL Command), commonly known as SQL Injection. The flaw exists in the feedback module of Online-Exam-System 2015, where user-supplied input through the fid parameter is not properly sanitized before being incorporated into SQL queries.

When an attacker provides specially crafted input containing SQL syntax through the fid parameter, the application processes this malicious input as part of the database query rather than treating it as data. This allows attackers to break out of the intended query structure and execute arbitrary SQL commands against the backend database.

The network-accessible nature of this vulnerability means that remote attackers can exploit it without any authentication requirements, making it particularly dangerous for internet-facing deployments.

Root Cause

The root cause of this vulnerability is insufficient input validation and the use of unsanitized user input directly in SQL query construction. The application fails to implement parameterized queries or prepared statements, which would properly separate SQL code from user data. Instead, the fid parameter value is concatenated directly into the SQL query string, allowing attackers to inject malicious SQL syntax that alters the query's logic.

Attack Vector

The attack vector is network-based, requiring no user interaction or prior authentication. An attacker can exploit this vulnerability by sending a crafted HTTP request to the feedback module endpoint with a malicious fid parameter value. The injected SQL code can be designed to:

• Extract sensitive data from the database using UNION-based or error-based injection techniques
• Bypass authentication mechanisms
• Modify or delete database records including exam results and user accounts
• Potentially execute system commands if database permissions allow

The vulnerability can be exploited through direct HTTP requests targeting the feedback functionality, where the fid parameter accepts malicious input. For detailed technical exploitation information, refer to the Exploit-DB #48529 entry and the VulnCheck SQL Injection Advisory.

Detection Methods for CVE-2020-37057

Indicators of Compromise

• Unusual database query patterns or errors in application logs related to the feedback module
• HTTP requests to feedback endpoints containing SQL keywords (UNION, SELECT, INSERT, DELETE, OR, AND) in the fid parameter
• Unexpected database access patterns or data exfiltration attempts
• Error messages revealing database structure or SQL syntax errors being returned to clients

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect SQL injection patterns in the fid parameter
• Deploy application-layer logging to capture and analyze requests to the feedback module
• Configure database audit logging to identify anomalous query execution patterns
• Use intrusion detection systems (IDS) with SQL injection signature rules targeting URL parameters

Monitoring Recommendations

• Monitor application logs for HTTP 500 errors or database error messages from the feedback module
• Set up alerts for requests containing encoded SQL injection payloads (URL encoding, hex encoding)
• Track database query execution times for anomalies that may indicate time-based blind SQL injection attempts
• Review access logs for repeated requests to feedback endpoints with varying fid parameter values

How to Mitigate CVE-2020-37057

Immediate Actions Required

• Restrict network access to the Online-Exam-System feedback module if not required for external users
• Deploy a Web Application Firewall (WAF) with SQL injection protection rules
• Implement input validation to whitelist only numeric values for the fid parameter
• Consider disabling the feedback module until a proper fix can be implemented

Patch Information

No official vendor patch has been identified in the available CVE data. The Online-Exam-System project is hosted on GitHub at the Online Exam System Repository. Organizations using this software should check the repository for any updates addressing this vulnerability or consider implementing manual code fixes using parameterized queries.

Workarounds

• Modify the application code to use prepared statements or parameterized queries for all database interactions involving the fid parameter
• Implement strict input validation to ensure the fid parameter only accepts integer values
• Deploy network segmentation to limit database access from the web application tier
• Use a reverse proxy with SQL injection filtering capabilities in front of the application

# Example WAF rule for ModSecurity to block SQL injection in fid parameter
SecRule ARGS:fid "@detectSQLi" \
    "id:1001,\
    phase:2,\
    deny,\
    status:403,\
    msg:'SQL Injection attempt detected in fid parameter',\
    log,\
    auditlog"