1. Introduction
Cisco Prime Network / Wireless Control System Health Monitor has a cross-site scripting vulnerability. This allows an attacker to inject malicious scripts into web pages viewed by users, potentially stealing cookies or performing actions on their behalf. Systems running the affected Health Monitor component are at risk. A successful exploit could compromise confidentiality and integrity of user sessions.
2. Technical Explanation
The vulnerability is a reflective cross-site scripting (XSS) flaw in the ‘requestUrl’ parameter of the web application. Input to this parameter isn’t properly sanitized, allowing an attacker to inject arbitrary script code. An attacker could craft a malicious URL and trick a user into visiting it. This would cause their browser to execute the injected script within the context of the vulnerable website. The vulnerability is tracked as CVE-2012-5990.
- Root cause: Missing input validation on the ‘requestUrl’ parameter allows arbitrary HTML and JavaScript code to be included in the response.
- Exploit mechanism: An attacker sends a specially crafted URL containing malicious JavaScript to a victim. When the victim clicks the link, the script executes within their browser session. For example:
https://[target]/healthmonitor/requestUrl= - Scope: Cisco Prime Network / Wireless Control System Health Monitor is affected. Specific versions are not detailed in the available information.
3. Detection and Assessment
Confirming vulnerability requires checking the version of Health Monitor running on web servers. A thorough assessment involves attempting to inject a test XSS payload.
- Quick checks: Access the Health Monitor web interface and check the version number displayed in the footer or “About” section.
- Scanning: Nessus plugin ID 62143 can detect this vulnerability. This is an example only, other scanners may also provide detection capabilities.
- Logs and evidence: Examine web server access logs for requests containing suspicious characters or script tags in the ‘requestUrl’ parameter.
4. Solution / Remediation Steps
Currently, there is no known solution for this vulnerability. Mitigation focuses on limiting access and monitoring for exploitation attempts.
4.1 Preparation
- Dependencies: No specific dependencies are known, but ensure you understand the impact of any network restrictions on other services. A roll back plan involves restoring from the previous backup or snapshot.
- Change window: Coordinate with relevant teams and obtain approval for implementing access controls.
4.2 Implementation
- Step 1: Restrict access to the Health Monitor web interface to only authorized personnel using firewall rules or access control lists (ACLs).
- Step 2: Implement a Web Application Firewall (WAF) with XSS protection enabled, configured to block requests containing suspicious script tags in the ‘requestUrl’ parameter.
- Step 3: Monitor web server logs for any attempts to exploit this vulnerability.
4.3 Config or Code Example
Before
# Allow access only from specific IP addresses
iptables -A INPUT -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -j DROP
After
# Allow access only from specific IP addresses
iptables -A INPUT -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -j DROP
4.4 Security Practices Relevant to This Vulnerability
Several security practices can help mitigate the risk of XSS vulnerabilities.
- Input validation: Validate all user-supplied input on both the client and server sides to prevent malicious code from being injected.
- Least privilege: Limit access to sensitive web interfaces like Health Monitor to only authorized personnel.
- Safe defaults: Configure systems with secure default settings, minimizing the attack surface.
4.5 Automation (Optional)
No specific automation scripts are available for this vulnerability due to the lack of a patch. However, you can automate firewall rule updates using configuration management tools like Ansible or Puppet.
5. Verification / Validation
Verify that access to the Health Monitor web interface is restricted and that attempts to inject XSS payloads are blocked by the WAF.
- Post-fix check: Verify that only authorized IP addresses can access the Health Monitor web interface using a network scan or firewall logs.
- Re-test: Attempt to access the Health Monitor web interface from an unauthorized IP address and confirm that the connection is blocked. Try injecting a test XSS payload through the ‘requestUrl’ parameter and verify it does not execute.
- Smoke test: Ensure authorized users can still access and use the core functionality of the Health Monitor web interface.
- Monitoring: Review web server logs for any suspicious activity or failed attempts to exploit this vulnerability.
# Example firewall log check (iptables)
iptables -L INPUT
# Expected output should show only allowed IP addresses accessing the interface
6. Preventive Measures and Monitoring
Proactive measures can help prevent similar vulnerabilities in the future.
- Baselines: Update security baselines to include input validation requirements for all web applications.
- Pipelines: Integrate static application security testing (SAST) tools into the CI/CD pipeline to identify potential XSS vulnerabilities during development.
- Asset and patch process: Implement a regular patch management cycle to ensure systems are updated with the latest security fixes as soon as they become available.
7. Risks, Side Effects, and Roll Back
Restricting access may impact legitimate users if not configured correctly.
- Risk or side effect 1: Restricting access too broadly could disrupt authorized users’ ability to manage the system. Mitigation involves carefully defining allowed IP addresses and monitoring for false positives.
- Roll back: Remove the firewall rules or WAF configuration changes to restore full access to the Health Monitor web interface. Restore from backup if necessary.
8. References and Resources
- Vendor advisory or bulletin: https://tools.cisco.com/bugsearch/bug/CSCud18375
- NVD or CVE entry: /cve/CVE-2012-5990
- Product or platform documentation relevant to the fix: No specific documentation available for this vulnerability. Refer to Cisco Prime Network / Wireless Control System Health Monitor configuration guides for general security best practices.