1. Introduction
The Apache Nifi Web Interface Detection vulnerability indicates that the web interface for Apache Nifi, a software project designed to automate data flow between systems, has been detected on a remote host. This matters because an unpatched Nifi instance could be exposed to potential attacks. Confidentiality, integrity and availability may all be impacted if exploited.
2. Technical Explanation
The vulnerability lies in the presence of the Apache Nifi web interface itself. While not a flaw *in* Nifi, its exposure can lead to reconnaissance and subsequent exploitation attempts. Attackers could identify vulnerable instances and attempt to exploit known weaknesses or misconfigurations within the application. NOTE: Nifi version 14.0 and later requires the server’s hostname to be added to nifi.web.https.host in nifi.properties to be scanned properly.
- Root cause: The web interface is accessible, indicating a potential attack surface.
- Exploit mechanism: An attacker could identify the Nifi version and known vulnerabilities through reconnaissance of the web interface. They may then attempt to exploit these weaknesses.
- Scope: Apache Nifi installations with an exposed web interface are affected.
3. Detection and Assessment
To confirm whether a system is vulnerable, first check for the presence of the web interface. Then verify the Nifi version.
- Quick checks: Access the Nifi web interface via a web browser to confirm its availability.
- Scanning: Nessus plugin ID 16824 can detect exposed Apache Nifi instances. This is an example only, and may require configuration.
- Logs and evidence: Check web server logs for requests accessing the Nifi web interface URL (typically port 8080).
curl -I http://<target_ip>:80804. Solution / Remediation Steps
The primary solution is to restrict access to the Nifi web interface or ensure it’s running behind appropriate authentication and authorization controls.
4.1 Preparation
- Dependencies: Ensure you have access to modify firewall rules or web server configurations. Roll back plan: Restore the original configuration files if issues arise.
- A change window may be needed for significant network modifications. Approval from a system owner is recommended.
4.2 Implementation
- Step 1: Restrict access to port 8080 via firewall rules, allowing only trusted IP addresses or networks.
- Step 2: Configure the Nifi web interface to require authentication (e.g., using SSL/TLS and user credentials).
- Step 3: If possible, place a reverse proxy in front of Nifi with strong authentication and authorization controls.
4.3 Config or Code Example
Before
# nifi.properties (example - no specific access control)
nifi.web.http.host=0.0.0.0
nifi.web.https.host=0.0.0.0
After
# nifi.properties (example - restricting access)
nifi.web.http.host=127.0.0.1 # or specific trusted IP
nifi.web.https.host=127.0.0.1 # or specific trusted IP
4.4 Security Practices Relevant to This Vulnerability
Several security practices can help mitigate this vulnerability type. Least privilege reduces the impact of a successful attack. Input validation prevents malicious data from being processed. Safe defaults minimize the initial attack surface.
- Practice 1: Least privilege – restrict access to services and ports only to authorized users and systems.
- Practice 2: Network segmentation – isolate Nifi instances within a secure network segment.
4.5 Automation (Optional)
# Example Bash script for firewall rule update (example only, adjust as needed)
#!/bin/bash
TARGET_IP="<target_ip>"
sudo ufw deny 8080 comment "Block Nifi web interface access"
sudo ufw allow from <trusted_ip> to any port 8080 comment "Allow trusted IP access"
sudo ufw reload
5. Verification / Validation
Confirm the fix by verifying that unauthorized access is blocked and authorized access functions correctly.
- Post-fix check: Attempt to access the Nifi web interface from an untrusted IP address; it should be unreachable.
- Re-test: Re-run the curl command from section 3, confirming that the interface is no longer accessible externally.
- Smoke test: Verify authorized users can still access and use the Nifi web interface.
- Monitoring: Check firewall logs for blocked connection attempts to port 8080 from untrusted sources. This is an example only.
curl -I http://<target_ip>:8080 # Should return "Connection refused" or similar error
6. Preventive Measures and Monitoring
Update security baselines to include restrictions on access to sensitive web interfaces. Implement checks in CI/CD pipelines to prevent deployment of systems with open ports. Establish a regular patch review cycle for all software, including Nifi.
- Baselines: Update your network security baseline to require restricted access to administrative web interfaces like Nifi.
- Pipelines: Add static analysis checks in CI/CD pipelines to identify exposed ports or insecure configurations.
- Asset and patch process: Review Nifi configuration files during regular asset reviews, ensuring proper access controls are in place.
7. Risks, Side Effects, and Roll Back
Restricting access could disrupt legitimate users if not configured correctly. Incorrect firewall rules may block all traffic to the server. To roll back, restore the original configuration files or revert the firewall changes.
- Risk or side effect 2: Service disruption – ensure proper testing to avoid unintended consequences.
- Roll back: Restore the original nifi.properties file and revert any firewall rule changes. Restart the Nifi service if necessary.
8. References and Resources
- Vendor advisory or bulletin: https://nifi.apache.org/