How to remediate – ExtCalendar ‘cat_id’ parameter SQL Injection

1. Introduction

The ExtCalendar ‘cat_id’ parameter SQL Injection vulnerability allows a remote attacker to inject malicious SQL code into the application through the ‘calendar.php’ script. This can lead to unauthorized access, data breaches, and compromise of the underlying database system. Systems running vulnerable versions of ExtCalendar are at risk, particularly those directly exposed to the internet. A successful exploit could result in loss of confidentiality, integrity, and availability of sensitive information.

2. Technical Explanation

• Exploit mechanism: An attacker crafts a malicious URL containing SQL injection code in the ‘cat_id’ parameter, which is then executed against the database when the script processes the request. For example, an attacker could inject ‘1’=’1 to bypass authentication.
• Scope: Affected versions of ExtCalendar are known to be vulnerable. The application is no longer actively maintained.

3. Detection and Assessment

To confirm vulnerability, check the installed version of ExtCalendar. A thorough assessment involves attempting a basic SQL injection test.

• Quick checks: Check for the presence of the ‘calendar.php’ script in the web application directory.
• Scanning: Nessus plugin ID 45746 can detect this vulnerability. This is an example only.
• Logs and evidence: Examine web server logs for requests to ‘calendar.php’ with suspicious ‘cat_id’ parameter values.

# No specific command available, check file presence manually

4. Solution / Remediation Steps

The recommended solution is to remove the affected ExtCalendar installation or switch to a different application due to lack of ongoing maintenance.

4.1 Preparation

• Ensure you have access to the web server file system and database credentials. A roll back plan involves restoring the backup.
• Change windows may be needed depending on business impact, requiring approval from IT management.

4.2 Implementation

1. Step 1: Delete the ExtCalendar installation directory from the web server file system.
2. Step 2: Remove any associated database entries related to ExtCalendar.
3. Step 3: Restart the web server service.

4.3 Config or Code Example

No configuration changes are needed as the solution involves removing the application.

Before

# ExtCalendar files present in web directory

After

# ExtCalendar files removed from web directory

4.4 Security Practices Relevant to This Vulnerability

Input validation and least privilege are key practices for preventing this type of issue.

• Practice 1: Input validation prevents malicious code from being processed by the application, mitigating SQL injection risks.
• Practice 2: Least privilege limits the impact of a successful exploit by restricting database access rights.

4.5 Automation (Optional)

No automation is provided as the solution involves removing the application.

5. Verification / Validation

Confirm that the ExtCalendar files have been removed and that requests to ‘calendar.php’ result in an error. Test key functionality of other web applications to ensure no disruption.

• Post-fix check: Verify that the ‘calendar.php’ script is no longer accessible via a web browser, resulting in a 404 or similar error.
• Re-test: Attempt to access the ‘calendar.php’ script again; it should not be reachable.
• Smoke test: Confirm other web application functionalities are working as expected.
• Monitoring: Monitor web server logs for any errors related to missing files or scripts. This is an example only.

# No specific command available, check file presence manually

6. Preventive Measures and Monitoring

Regular security baselines and secure coding practices can prevent similar vulnerabilities.

• Baselines: Update web application security baselines to include input validation requirements.
• Pipelines: Implement Static Application Security Testing (SAST) in the CI/CD pipeline to identify potential SQL injection vulnerabilities during development.
• Asset and patch process: Regularly review installed applications for known vulnerabilities and consider removal of unsupported software.

7. Risks, Side Effects, and Roll Back

Removing ExtCalendar may disrupt any functionality that relies on it. A roll back involves restoring the backed-up web application directory.

• Risk or side effect 2: Potential downtime during file deletion and server restart. Mitigation is to schedule changes during off-peak hours.
• Roll back: Restore the backed-up web application directory and database. Restart the web server service.

8. References and Resources

Links to official advisories and documentation related to this vulnerability.

• Vendor advisory or bulletin: SecurityFocus BID 45746
• NVD or CVE entry: No specific CVE is listed for ExtCalendar, but the vulnerability is documented on SecurityFocus.
• Product or platform documentation relevant to the fix: N/A – application is no longer maintained.