How to remediate – HNAP Detection

1. Introduction

The remote device has HNAP enabled. The Home Network Administration Protocol (HNAP) is a SOAP-based protocol used for administrative control of networked devices. Enabling HNAP can create an attack vector, allowing unauthorized access to the device’s configuration. This affects home routers and similar embedded systems. A successful exploit could lead to loss of confidentiality, integrity, and availability of the device.

2. Technical Explanation

HNAP allows remote management via SOAP requests. The vulnerability exists because the service is enabled by default on many devices without strong authentication or access controls. An attacker can send crafted SOAP messages to modify device settings. There are no known CVEs associated with HNAP detection itself, but exploitation of HNAP is possible. For example, an attacker could change the router’s administrator password or firmware configuration.

• Root cause: The HNAP service is enabled without sufficient security measures.
• Exploit mechanism: An attacker sends malicious SOAP requests to the HNAP endpoint.
• Scope: Home routers, embedded devices running a vulnerable version of HNAP.

3. Detection and Assessment

You can confirm if a system is vulnerable by checking for the presence of the HNAP service. A quick check involves examining the device’s web interface or configuration files. For thorough assessment, use network scanning tools to identify open ports associated with HNAP.

• Quick checks: Check the router’s administration panel for an enabled HNAP option.
• Scanning: Nessus plugin 78450add and 11760f94 can detect HNAP. These are examples only.
• Logs and evidence: Look for SOAP requests in network traffic captures or device logs, if available.

nmap -p 80  --script http-soapui

4. Solution / Remediation Steps

To fix this issue, limit incoming traffic to the port used by HNAP or disable it if not needed. These steps are small and testable. Only apply these steps to devices where HNAP is required.

4.1 Preparation

• Dependencies: Ensure you have access credentials for the router’s administration panel. Roll back plan: Restore from backup if issues occur.
• Change window: Consider a maintenance window to minimize disruption. Approval may be needed by network administrators.

4.2 Implementation

1. Step 1: Log in to your router’s administration panel.
2. Step 2: Navigate to the HNAP settings (usually under Administration or Advanced Settings).
3. Step 3: Disable HNAP if it is not required. Alternatively, restrict access using firewall rules.

4.3 Config or Code Example

Before

HNAP Enabled: Yes

After

HNAP Enabled: No

4.4 Security Practices Relevant to This Vulnerability

Several security practices can help prevent this issue. Least privilege limits the impact of exploitation, while input validation blocks unsafe data. Safe defaults reduce the attack surface by disabling unnecessary services.

• Practice 1: Apply least privilege principles to all accounts and services.
• Practice 2: Use safe default configurations that disable unnecessary features like HNAP.

4.5 Automation (Optional)

Automation is not generally suitable for this vulnerability due to the variety of router interfaces.

5. Verification / Validation

Confirm the fix by checking if the HNAP service is disabled or access is restricted. Re-run the earlier detection methods to verify the issue is resolved. Perform a simple smoke test to ensure basic functionality remains intact.

• Post-fix check: Check the router’s administration panel and confirm that HNAP is disabled.
• Re-test: Run the nmap command from section 3 and confirm no HNAP service is detected.
• Smoke test: Verify you can still access the internet through the router.
• Monitoring: Monitor network traffic for any unexpected SOAP requests to the router’s IP address.

nmap -p 80  --script http-soapui

6. Preventive Measures and Monitoring

Update security baselines to include HNAP disabling as a standard configuration. Implement checks in CI/CD pipelines to prevent the deployment of devices with HNAP enabled by default. Maintain a sensible patch or config review cycle.

• Baselines: Update your router security baseline to require HNAP to be disabled unless specifically needed.
• Pipelines: Include configuration scanning in your deployment pipeline to identify devices with HNAP enabled.
• Asset and patch process: Review router configurations regularly for unnecessary services like HNAP.

7. Risks, Side Effects, and Roll Back

• Risk or side effect 1: Disabling HNAP could affect remote management features.
• Roll back: Restore the router’s configuration from the backup created in step 4.1.

8. References and Resources

Refer to official advisories for accurate information about this vulnerability.

• Vendor advisory or bulletin: http://www.nessus.org/u?78450add
• NVD or CVE entry: Not applicable for HNAP detection itself.
• Product or platform documentation relevant to the fix: http://www.nessus.org/u?11760f94