1. Introduction
The airVision NVR path Parameter Traversal Arbitrary File Access vulnerability allows an unauthenticated attacker to read arbitrary files on a remote host running the affected application. This could lead to sensitive information disclosure, impacting confidentiality. Systems running airVision NVR are typically at risk.
2. Technical Explanation
The airVision NVR web server fails to properly sanitize user-supplied input to the ‘path’ parameter of the ‘views/file.php’ script. An attacker can exploit this by sending a crafted request containing directory traversal characters in the ‘path’ parameter, allowing them to access files outside the intended directory. This is due to missing input validation on the path parameter.
- Root cause: Missing input validation of the ‘path’ parameter within the ‘views/file.php’ script.
- Exploit mechanism: An attacker sends a request with a malicious ‘path’ parameter containing directory traversal sequences (e.g., ‘../’). This allows access to files outside the web root. For example, sending a request like
http://target/views/file.php?path=../../../../../etc/passwdcould attempt to read the /etc/passwd file. - Scope: airVision NVR application. Specific versions are not explicitly stated in the available information.
3. Detection and Assessment
To confirm vulnerability, check the installed version of airVision NVR. A thorough method involves attempting to access files outside the web root using a crafted request.
- Quick checks: Check the application’s version information via its user interface or by inspecting HTTP headers.
- Scanning: Nessus vulnerability ID 55921 can be used as an example, but may not cover all versions.
- Logs and evidence: Monitor web server logs for requests containing directory traversal characters (e.g., ‘../’, ‘%2e%2e/’) in the ‘path’ parameter of ‘views/file.php’.
# No specific command available to confirm exposure directly, focus on version checking and log analysis.4. Solution / Remediation Steps
Currently, there is no known solution for this vulnerability at this time. Implement mitigating controls until a patch becomes available.
4.1 Preparation
- Dependencies: None known. Rollback plan: Restore from backup or revert any applied configurations.
4.2 Implementation
- Step 1: Monitor web server logs for suspicious activity, specifically requests containing directory traversal characters in the ‘path’ parameter of ‘views/file.php’.
- Step 2: Implement a Web Application Firewall (WAF) rule to block requests with directory traversal sequences in the ‘path’ parameter.
4.3 Config or Code Example
Before
# No code example available as the vulnerability is in the application logic, not directly configurable.After
# WAF rule example (syntax varies by WAF vendor): Block requests containing "../" or "%2e%2e/" in the 'path' parameter of ‘views/file.php’.4.4 Security Practices Relevant to This Vulnerability
Several security practices can help mitigate this vulnerability type.
- Practice 1: Input validation is crucial to block unsafe data and prevent directory traversal attacks.
- Practice 2: Least privilege limits the impact if an attacker successfully exploits the vulnerability by restricting access to sensitive files.
4.5 Automation (Optional)
No automation script available at this time.
# No relevant script provided due to lack of a specific fix.5. Verification / Validation
- Post-fix check: Attempt to access a file outside the web root (e.g.,
http://target/views/file.php?path=../../../../../etc/passwd). The request should be blocked by the WAF or other controls. - Re-test: Repeat the earlier detection attempt; it should no longer succeed in accessing files outside the web root.
- Smoke test: Verify that legitimate users can still access and monitor IP cameras through the airVision NVR application.
# Expected output: HTTP 403 Forbidden or similar error message indicating blocked access.6. Preventive Measures and Monitoring
Update security baselines to include input validation requirements for web applications. Implement CI/CD pipeline checks to scan for directory traversal vulnerabilities.
- Baselines: Update a security baseline or policy to require strict input validation on all user-supplied data, especially file paths.
- Pipelines: Add Static Application Security Testing (SAST) tools to the CI/CD pipeline to identify potential directory traversal vulnerabilities in code.
- Asset and patch process: Implement a regular patch review cycle for airVision NVR and other web applications.
7. Risks, Side Effects, and Roll Back
- Risk or side effect 1: False positives from WAF rules blocking legitimate traffic. Mitigation: Fine-tune WAF rules based on observed traffic patterns.
- Roll back: Remove the implemented WAF rule or revert any applied configurations. Restore from backup if necessary.
8. References and Resources
Links to official advisories and trusted documentation.
- Vendor advisory or bulletin: https://www.ubnt.com/
- NVD or CVE entry: No specific CVE available at this time.
- Product or platform documentation relevant to the fix: Refer to Ubiquiti’s airVision NVR documentation for security best practices.