How to remediate – MySQLjs SQL Injection Authentication Bypass

1. Introduction

MySQLjs SQL Injection Authentication Bypass is a vulnerability where unsanitised input can be used in SQL queries, allowing attackers to bypass authentication and access sensitive data. This affects applications using the mysqljs/mysql library for database interactions. Successful exploitation could lead to full compromise of the database, impacting confidentiality, integrity, and availability of application data.

2. Technical Explanation

An SQL injection occurs because the mysqljs/mysql library handles different value types inconsistently when escaping parameters. This allows an attacker to craft a malicious input that bypasses these escape mechanisms. The scanner detected this by successfully authenticating with a crafted request.

• Root cause: Inconsistent parameter escaping in the mysqljs/mysql library across various data types.
• Exploit mechanism: An attacker submits a specially crafted value as a login credential, which is then processed without proper sanitisation and injected into an SQL query, bypassing authentication checks. For example, submitting a string containing malicious SQL code within a username or password field.
• Scope: Applications using the mysqljs/mysql library are affected. Specific versions may be more vulnerable than others; see references for details.

3. Detection and Assessment

Confirming vulnerability requires checking your application’s use of the mysqljs/mysql library and testing its input handling.

• Quick checks: Verify the version of the mysqljs/mysql package used in your project using `npm list mysql`.
• Scanning: Static Application Security Testing (SAST) tools can identify potential SQL injection vulnerabilities within application code, but may not detect this specific bypass. Look for rules related to unsanitised database queries.
• Logs and evidence: Examine application logs for failed login attempts followed by successful authentications with unusual or unexpected input parameters. Check for error messages related to SQL syntax errors.

npm list mysql

4. Solution / Remediation Steps

The following steps will help fix the issue and prevent SQL injection attacks.

4.1 Preparation

• Stop the application service to avoid conflicts during configuration updates. A roll back plan involves restoring the previous database backup and redeploying the original application code.
• Changes should be approved by a senior developer or security engineer.

4.2 Implementation

4.3 Config or Code Example

Before

const connection = mysql.createConnection({
  host: 'localhost',
  user: 'your_user',
  password: 'your_password',
  database: 'your_database'
});

After

const connection = mysql.createConnection({
  host: 'localhost',
  user: 'your_user',
  password: 'your_password',
  database: 'your_database',
  stringifyObjects: true
});

4.4 Security Practices Relevant to This Vulnerability

List only practices that directly address this vulnerability type. Use neutral wording and examples instead of fixed advice. For example: least privilege, input validation, safe defaults, secure headers, patch cadence.

• Practice 2: Least Privilege – Grant database users only the minimum necessary permissions required for their tasks. This limits the potential damage from a successful injection attack.

4.5 Automation (Optional)

# Example Bash script to update package.json (use with caution!)
# This assumes you are using npm
# Replace 'your-project-directory' with the actual path
cd your-project-directory
npm install mysql@latest --save

5. Verification / Validation

Confirming the fix involves retesting the vulnerability and verifying application functionality.

• Post-fix check: Verify that `npm list mysql` shows an updated version of the library, or confirm your code changes have been deployed.
• Monitoring: Monitor application logs for any unexpected errors or suspicious activity related to database queries. Look for patterns indicating potential injection attempts.

npm list mysql

6. Preventive Measures and Monitoring

Suggest only measures that are relevant to the vulnerability type. Use “for example” to keep advice conditional, not prescriptive.

• Baselines: Update your security baseline to include requirements for secure coding practices, such as input validation and parameterised queries.
• Pipelines: Integrate Static Application Security Testing (SAST) tools into your CI/CD pipeline to automatically identify potential SQL injection vulnerabilities during development.
• Asset and patch process: Implement a regular patch management cycle to ensure that all software components are up-to-date with the latest security fixes.

7. Risks, Side Effects, and Roll Back

• Risk or side effect 2: Incorrectly implemented type checking could lead to application errors or unexpected behaviour.
• Roll back: Restore the previous database backup and redeploy the original application code. If you updated the package, revert to the older version using `npm install mysql@ –save`.

8. References and Resources

• Vendor advisory or bulletin: https://flattsecurity.medium.com/finding-an-unseen-sql-injection-by-bypassing-escape-functions-in-mysqljs-mysql-90b27f6542b4
• NVD or CVE entry: Not available at time of writing, check NVD database.
• Product or platform documentation relevant to the fix: https://github.com/mysqljs/mysql