SQL Injection Flaw In Sourcecodester Student Clearance System

This article details a critical SQL injection vulnerability discovered in the Sourcecodester Online Student Clearance System Project V1.0. This vulnerability poses a significant security risk, potentially allowing attackers to gain unauthorized access to sensitive data. This comprehensive analysis covers the affected product, vulnerability details, potential impact, and recommended remediation steps. Our goal is to provide clear, actionable information to help developers and system administrators secure their applications.

Affected Product

• Product Name: Online Student Clearance System
• Vendor Homepage: https://www.sourcecodester.com/php/17892/online-clearance-system.html
• Submitter: yudeshui
• Vulnerable File: /Admin/login.php
• Version: V1.0
• Software Link: https://www.sourcecodester.com/sites/default/files/download/Senior%20Walter/student_clearance_system_aurthur_javis.zip

It's crucial to identify the affected product accurately to ensure the correct application of patches and mitigation strategies. The Online Student Clearance System, a web application designed to streamline student clearance processes, is the target of this vulnerability. Knowing the vendor homepage and software link allows users to verify the authenticity of the product and access official resources. The specific vulnerable file, /Admin/login.php, pinpoints the exact location of the security flaw, enabling focused remediation efforts. Finally, identifying the version as V1.0 clarifies the scope of the vulnerability, as subsequent versions may include fixes.

Vulnerability Details

Vulnerability Type

• SQL Injection

Root Cause

The root cause of this vulnerability lies in the insufficient input validation within the /Admin/login.php file. Specifically, the application fails to properly sanitize the txtusername parameter before using it in an SQL query. This lack of sanitization allows attackers to inject malicious SQL code through the txtusername parameter. The injected code is then executed by the database, potentially leading to unauthorized data access or manipulation. Input validation is a critical aspect of secure coding practices, and its absence in this case leads directly to the SQL injection vulnerability. This means that instead of treating the user-provided input as mere data, the system inadvertently interprets it as executable SQL commands.

Impact

The impact of this SQL injection vulnerability is severe, as it can lead to:

• Unauthorized database access: Attackers can bypass authentication mechanisms and directly access the database.
• Sensitive data leakage: Confidential student information, administrative credentials, and other sensitive data can be exposed.
• Data tampering: Attackers can modify or delete data within the database, potentially disrupting the system's functionality and integrity.
• Comprehensive system control: In some scenarios, successful SQL injection can lead to complete control over the server hosting the application.
• Service interruption: Attackers can inject code that causes the database server to crash, leading to denial of service.

The potential for data breaches, system compromise, and operational disruption makes this a high-severity vulnerability. The ability to tamper with student records, for instance, could have serious implications for academic integrity and institutional reputation. The risk of sensitive data leakage is particularly concerning, given the potential for identity theft and other malicious activities.

Description

A critical SQL injection vulnerability was discovered in the /Admin/login.php file during a security review of the Online Student Clearance System. This vulnerability arises from the inadequate validation of the txtusername parameter, which allows attackers to inject malicious SQL queries. By exploiting this flaw, attackers can gain unauthorized access to the database, modify or delete data, and access sensitive information. Exploitation of this vulnerability requires no prior authentication, making it particularly dangerous. Immediate remediation is necessary to ensure system security and protect data integrity. The flaw allows attackers to bypass normal access controls, posing a direct threat to the confidentiality, integrity, and availability of the system. The ease with which this vulnerability can be exploited further underscores the urgency of addressing it.

Vulnerability Details and Proof of Concept (POC)

The following demonstrates how an attacker can exploit this SQL injection vulnerability:

---
Parameter: txtusername (POST)
    Type: boolean-based blind
    Title: OR boolean-based blind - WHERE or HAVING clause
    Payload: txtusername=-9758' OR 4036=4036-- mfou&txtpassword=test&btnlogin=Sign In

    Type: time-based blind
    Title: MySQL >= 5.0.12 AND time-based blind (query SLEEP)
    Payload: txtusername=test' AND (SELECT 7488 FROM (SELECT(SLEEP(5)))YATu)-- NIhz&txtpassword=test&btnlogin=Sign In

---

These payloads demonstrate how an attacker can manipulate the SQL query by injecting malicious code into the txtusername parameter. The boolean-based blind SQL injection attempts to infer the truth value of a condition by observing the application's response. The time-based blind SQL injection uses the SLEEP() function to introduce a delay, allowing the attacker to determine the truth value of a condition based on the response time. These techniques allow attackers to extract data or perform unauthorized actions without directly seeing the results of their queries.

SQLmap

The following sqlmap command can be used to automatically detect and exploit this SQL injection vulnerability:

sqlmap -u "http://dede:802/Admin/login.php" \
       --data="txtusername=test&txtpassword=test&btnlogin=Sign+In" \
       --batch \
       --level=5 \
       --risk=3

This command instructs sqlmap to test the specified URL (http://dede:802/Admin/login.php) for SQL injection vulnerabilities. The --data parameter provides the necessary POST data for the login form. The --batch option tells sqlmap to automatically answer questions. The --level=5 and --risk=3 parameters increase the thoroughness of the scan. The use of sqlmap highlights the ease with which this vulnerability can be detected and exploited by automated tools, emphasizing the need for proactive security measures.

This image visually confirms the presence of the SQL injection vulnerability, further substantiating the need for immediate action. The screenshot likely shows sqlmap successfully identifying and exploiting the vulnerability, providing concrete evidence of the risk.

Vulnerable Parameter

• txtusername parameter

The txtusername parameter is the primary entry point for the SQL injection attack. This parameter, used for username input during login, is not properly sanitized, allowing malicious SQL code to be injected. Identifying the specific vulnerable parameter is crucial for targeted remediation efforts. Developers can focus their attention on securing this particular input field, significantly reducing the risk of exploitation.

Suggested Repair

To mitigate this SQL injection vulnerability, the following steps are recommended:

1. Use Prepared Statements and Parameter Binding: Prepared statements prevent SQL injection by separating SQL code from user input. When using prepared statements, user input is treated as data and not interpreted as SQL code. This approach ensures that even if an attacker injects SQL code, it will be treated as a string literal rather than an executable command. Prepared statements are a fundamental defense against SQL injection attacks, and their implementation is highly recommended.
2. Input Validation and Filtering: Strictly validate and filter user input data to ensure it conforms to the expected format. This includes checking the length, format, and content of the input. Implement whitelisting to only allow known safe characters and patterns, and reject anything else. Input validation is a crucial layer of defense that can prevent many common web vulnerabilities.
3. Minimize Database User Permissions: Ensure that the account used to connect to the database has the minimum necessary permissions. Avoid using accounts with elevated privileges (such as 'root' or 'admin') for routine operations. By limiting database user permissions, the potential damage from a successful SQL injection attack is significantly reduced. An attacker who gains access through SQL injection will only be able to perform actions allowed by the compromised user account.
4. Regular Security Audits: Regularly conduct code and system security audits to promptly identify and fix potential security vulnerabilities. Security audits should include both automated scanning and manual code review to ensure comprehensive coverage. Regular audits help identify vulnerabilities before they can be exploited by attackers.

Conclusion

The SQL injection vulnerability in the Sourcecodester Online Student Clearance System V1.0 poses a significant security risk. By understanding the root cause, potential impact, and recommended remediation steps, developers and system administrators can take proactive measures to protect their systems and data. Implementing prepared statements, rigorous input validation, minimizing database user permissions, and conducting regular security audits are crucial steps in mitigating this vulnerability and ensuring the overall security of the application. For more information on SQL injection prevention, please visit the OWASP (Open Web Application Security Project) website at https://owasp.org.