1. Introduction
SecurityCenter contains a cross-site scripting vulnerability in the ‘devform.php’ script’s message parameter. This means an attacker could inject malicious code into a user’s browser, potentially stealing cookies or performing actions as that user. This affects web servers running SecurityCenter and impacts confidentiality, integrity, and availability of the system.
2. Technical Explanation
The ‘devform.php’ script does not properly validate input provided to the ‘message’ parameter. An attacker can supply crafted HTML or JavaScript code as part of this parameter which will then be executed in a user’s browser when viewing the affected page. This is known as stored cross-site scripting, as the malicious content may persist on the server.
- Root cause: Missing input validation for the ‘message’ parameter within the ‘devform.php’ script.
- Exploit mechanism: An attacker submits a crafted message containing JavaScript code to the vulnerable form. When another user views this message, the injected script executes in their browser. For example, submitting `` would display an alert box.
- Scope: Tenable Network Security SecurityCenter installations are affected.
3. Detection and Assessment
Confirming vulnerability requires checking for the presence of the script and then testing its input handling.
- Quick checks: Check if the ‘devform.php’ file exists on the server in the expected SecurityCenter installation directory.
- Scanning: Nessus plugin ID 68791 can detect this vulnerability, but results should be verified manually.
- Logs and evidence: Web server logs may show requests containing suspicious characters or script tags submitted to ‘devform.php’.
ls -l /opt/tenable/securitycenter/devform.php #Example command placeholder: check for the file's existence
4. Solution / Remediation Steps
The best solution is to remove or restrict access to the vulnerable script.
4.1 Preparation
- Ensure you have appropriate permissions to modify files on the server. A roll back plan is to restore from backup.
- A change window should be scheduled with approval from the security team.
4.2 Implementation
- Step 1: Remove the ‘devform.php’ script from the SecurityCenter installation directory using the command line.
- Step 2: If removal is not possible, restrict access to the script using web server configuration (e.g., .htaccess or virtual host settings).
4.3 Config or Code Example
Before
# File exists in installation directory, accessible via web serverAfter
# File removed from installation directory OR access restricted via web server configuration. For example: <Files devform.php> Order Deny,Allow Deny from all </Files> in .htaccess4.4 Security Practices Relevant to This Vulnerability
Several security practices can help prevent this type of issue.
- Practice 1: Input validation is essential to block malicious code from being processed by the application.
- Practice 2: Least privilege limits the impact if an attacker successfully exploits a vulnerability.
4.5 Automation (Optional)
# Example Bash script to remove the file:
# !/bin/bash
# rm -f /opt/tenable/securitycenter/devform.php
# Ensure correct path before running!
5. Verification / Validation
Confirming the fix involves checking that the script is removed or inaccessible and re-testing for vulnerability.
- Post-fix check: Verify that ‘devform.php’ no longer exists in the installation directory, or that access is denied via web server configuration.
- Re-test: Attempt to submit a malicious payload through the form (if it still exists). The payload should not execute.
- Monitoring: Monitor web server logs for any attempts to access ‘devform.php’.
ls -l /opt/tenable/securitycenter/devform.php #Post-fix command and expected output: "No such file or directory"6. Preventive Measures and Monitoring
Regular security assessments and patching are important to prevent this vulnerability type.
- Baselines: Update your security baseline to include checks for known vulnerable scripts and configurations.
- Pipelines: Implement static application security testing (SAST) in your CI/CD pipeline to identify input validation issues early on.
- Asset and patch process: Establish a regular patch cycle for all software, including SecurityCenter.
7. Risks, Side Effects, and Roll Back
Removing ‘devform.php’ may affect functionality if it is used by other parts of the application (unlikely).
- Roll back: Restore the ‘devform.php’ file from backup if functionality is broken.
8. References and Resources
- Vendor advisory or bulletin: https://www.tenable.com/security/tns-2013-01
- NVD or CVE entry: CVE-2013-5911