1. Introduction
The Firefly Media Server Limited Directory Traversal Admin Credential Leak vulnerability (CVE-2016-6475) allows an attacker to retrieve arbitrary files from the server, potentially bypassing authentication. This could lead to exposure of sensitive information like configuration details or user data. Systems running vulnerable versions of Firefly Media Server on Windows are affected. The likely impact is high confidentiality loss, with potential integrity and availability impacts if configuration files are modified.
2. Technical Explanation
The vulnerability stems from insufficient input validation when handling file requests to the web server component of Firefly Media Server (mt-daapd). An attacker can manipulate the request path to access files outside the intended ‘admin-root’ directory, including parent directories. This allows retrieval of sensitive files on the system.
- Root cause: The application does not properly sanitize user input when constructing file paths, allowing traversal characters (e.g., “..”) to be used.
- Exploit mechanism: An attacker sends a crafted HTTP request containing malicious path parameters that navigate outside the ‘admin-root’ directory. For example, requesting
/admin/../../../../etc/passwdcould retrieve the system’s password file. - Scope: Windows systems running Firefly Media Server (mt-daapd) versions prior to a patched release are affected.
3. Detection and Assessment
Confirming vulnerability requires checking the installed version of Firefly Media Server. A thorough assessment involves attempting to retrieve files outside the expected directory structure.
- Quick checks: Use PowerShell to check the application’s version:
Get-ItemProperty "HKLM:SOFTWAREmt-daapd" | Select-Object Version - Scanning: Nessus plugin ID 1048967 can detect this vulnerability. Other scanners may have similar signatures.
- Logs and evidence: Check web server logs for requests containing traversal characters (e.g., “..”) in the file path parameters. Look for access attempts to files outside of the ‘admin-root’ directory.
Get-ItemProperty "HKLM:SOFTWAREmt-daapd" | Select-Object Version4. Solution / Remediation Steps
Currently, there is no known solution available at this time. Mitigation focuses on limiting access and monitoring for exploitation attempts. Patching the software when a release becomes available is the primary remediation step.
4.1 Preparation
- Ensure you have access to the server’s file system and administrative privileges. A roll back plan involves restoring the backed-up configuration files and restarting the service.
4.2 Implementation
- Step 1: Monitor web server logs for suspicious activity, specifically requests containing directory traversal characters (e.g., “..”).
- Step 2: Restrict access to the Firefly Media Server administration interface using firewall rules or IP address filtering. Limit access only to trusted networks and users.
4.3 Config or Code Example
Since there is no known patch, a config example isn’t applicable at this time.
4.4 Security Practices Relevant to This Vulnerability
Several security practices can help mitigate the risk of directory traversal vulnerabilities. Least privilege reduces the impact if exploited. Input validation blocks unsafe data and prevents malicious requests. Safe defaults ensure secure configurations are used by default.
- Practice 1: Implement least privilege access control to limit the potential damage from a successful exploit.
- Practice 2: Enforce strict input validation on all user-supplied data, including file paths, to prevent traversal characters and other malicious inputs.
4.5 Automation (Optional)
Automation is not directly applicable without a patch.
5. Verification / Validation
Verification involves confirming that the web server no longer responds to requests containing directory traversal attempts. A negative test confirms that access to sensitive files outside the ‘admin-root’ directory is blocked.
- Post-fix check: Attempt a request with a directory traversal path (e.g.,
/admin/../../../../etc/passwd). The server should return an error or deny access. - Re-test: Re-run the initial detection method to confirm that the vulnerability is no longer present.
- Monitoring: Monitor web server logs for any further attempts to exploit the directory traversal vulnerability.
Attempt a request with a directory traversal path (e.g., /admin/../../../../etc/passwd). The server should return an error or deny access.6. Preventive Measures and Monitoring
Regular security baselines and policy updates are essential for preventing similar vulnerabilities. Implementing checks in CI/CD pipelines can stop the same fault from reaching production. A sensible patch review cycle reduces exposure to known threats.
- Baselines: Update your security baseline or policy to include requirements for input validation and secure file handling practices.
- Asset and patch process: Establish a regular patch review cycle to ensure timely application of security updates.
7. Risks, Side Effects, and Roll Back
Restricting access may impact legitimate users if not configured correctly. Incorrect firewall rules could block necessary traffic. Roll back involves restoring the original configuration files and restarting the service.
- Roll back: Restore the backed-up Firefly Media Server configuration files and restart the service to return to the previous state.
8. References and Resources
Official advisories provide detailed information about this vulnerability.
- Vendor advisory or bulletin: https://www.securityfocus.com/archive/1/484763
- NVD or CVE entry: https://nvd.nist.gov/vuln/detail/CVE-2016-6475
- Product or platform documentation relevant to the fix: No specific documentation is available at this time due to lack of a patch.