How to remediate – Oracle 9iAS PL/SQL Gateway Web Admin Interface Null Authentica…

1. Introduction

The Oracle 9iAS PL/SQL Gateway Web Admin Interface Null Authentication vulnerability affects applications using Oracle 9i Application Server. By default, no authentication is required to access its configuration page, allowing attackers to modify application settings. This impacts systems running the affected software and could lead to a loss of data integrity or denial of service.

2. Technical Explanation

The vulnerability stems from a missing authentication check on the PL/SQL Gateway Web Admin Interface. An attacker can directly access the configuration page without providing credentials, potentially altering application behaviour. This is tracked as CVE-2002-0561. A simple example would be an attacker changing a PL/SQL procedure to return incorrect data or disable critical functionality.

• Root cause: Absence of authentication on the DAD configuration page within the Apache web server module for PL/SQL support.
• Exploit mechanism: An attacker sends an HTTP request directly to the configuration URL without any credentials.
• Scope: Oracle 9i Application Server is affected.

3. Detection and Assessment

Confirming vulnerability requires checking access permissions to the DAD configuration page. A thorough method involves attempting to modify a test PL/SQL application.

• Quick checks: Check the version of Oracle 9i Application Server using the `opmnctl status` command.
• Scanning: Nessus plugin ID 16874 may detect this vulnerability as an example.
• Logs and evidence: Apache access logs should be checked for requests to the DAD configuration page without authentication details.

opmnctl status

4. Solution / Remediation Steps

Restrict access to the relevant page by editing the wdbsvr.app file.

4.1 Preparation

• Ensure you have appropriate permissions to edit system configuration files. Change windows may be required depending on your organisation’s policies.

4.2 Implementation

1. Step 1: Open the `/Apache/modplsql/cfg/wdbsvr.app` file in a text editor.
2. Step 2: Add an authentication requirement to the DAD configuration section. For example, add `auth_realm /`.
3. Step 3: Save the changes to the `wdbsvr.app` file.
4. Step 4: Restart the Oracle Application Server using `opmnctl restartall`.

4.3 Config or Code Example

Before

DAD / myapp directory=/var/www/myapp

After

auth_realm /
DAD / myapp directory=/var/www/myapp

4.4 Security Practices Relevant to This Vulnerability

Several security practices can help prevent this type of issue.

• Practice 1: Least privilege access to limit the impact if an attacker gains unauthorized access.
• Practice 2: Secure defaults, ensuring authentication is enabled by default for sensitive interfaces.

4.5 Automation (Optional)

Automation scripts are not recommended due to potential service disruption. Manual configuration changes are preferred in this case.

5. Verification / Validation

• Post-fix check: Attempting to access the DAD configuration page should now prompt for authentication.
• Re-test: Re-run the initial assessment attempt to modify a test PL/SQL application; it should fail due to missing credentials.
• Monitoring: Check Apache access logs for failed authentication attempts to the DAD configuration page as an example of a regression indicator.

Attempting to access the DAD config URL should now return a 401 Unauthorized error.

6. Preventive Measures and Monitoring

Regular security baselines can help prevent this issue.

• Baselines: Update your security baseline or policy to include authentication requirements for all sensitive web interfaces, such as the CIS Oracle Application Server Benchmark.
• Pipelines: Implement static analysis tools in CI/CD pipelines to identify missing authentication checks during development.
• Asset and patch process: Review configuration changes regularly and maintain a sensible patch cycle for critical software components.

7. Risks, Side Effects, and Roll Back

Incorrectly configuring the `wdbsvr.app` file could prevent access to PL/SQL applications.

• Risk or side effect 1: Incorrect configuration may cause service disruption. Mitigation is restoring the original `wdbsvr.app` file.
• Risk or side effect 2: Changes may require application restarts, causing temporary downtime.
• Roll back:
  1. Step 1: Restore the original `/Apache/modplsql/cfg/wdbsvr.app` file from backup.
  2. Step 2: Restart the Oracle Application Server using `opmnctl restartall`.

8. References and Resources

Links to sources that match this exact vulnerability.

• Vendor advisory or bulletin: http://www.nessus.org/u?ffaefc17
• NVD or CVE entry: CVE-2002-0561
• Product or platform documentation relevant to the fix: Oracle documentation on PL/SQL Gateway configuration.