How to remediate – Apache Hadoop HDFS NameNode Web Detection

1. Introduction

The Apache Hadoop HDFS NameNode Web Detection vulnerability identifies a web interface exposed on a Hadoop Distributed File System (HDFS) cluster’s NameNode server. This can allow unauthorized access to sensitive information and potentially lead to further compromise of the system. Affected systems are typically those running Hadoop clusters with an active NameNode service. A successful exploit could result in information disclosure, impacting confidentiality.

2. Technical Explanation

The vulnerability occurs because the HDFS NameNode web interface is enabled by default and may not be adequately secured. An attacker can remotely access this interface to gather information about the Hadoop cluster configuration and potentially identify further attack vectors. There is no known CVE associated with this specific detection, but it represents a misconfiguration risk. For example, an attacker could discover the Namenode’s web UI and enumerate users or other sensitive data.

• Root cause: The HDFS NameNode web interface is enabled without sufficient access controls.
• Exploit mechanism: An attacker connects to the NameNode’s default web port (typically 50070) via a web browser and accesses available information.
• Scope: Hadoop Distributed File Systems (HDFS) clusters running with an active NameNode service.

3. Detection and Assessment

You can confirm if your system is vulnerable by checking for the presence of the NameNode web interface and verifying its accessibility.

• Quick checks: Use netstat to check if port 50070 (default) is listening.
• Scanning: Nessus plugin ID 90ac656 can detect this vulnerability. This is an example only; other scanners may also provide detection capabilities.
• Logs and evidence: Check system logs for any access attempts to port 50070.

netstat -tulnp | grep 50070

4. Solution / Remediation Steps

The following steps outline how to limit incoming traffic to the NameNode web interface, mitigating the risk of unauthorized access.

4.1 Preparation

• Dependencies: Ensure you have appropriate firewall rules management tools available. Roll back plan: Restore the original configuration files if necessary.
• Change window needs: This change can be implemented during a maintenance window, but isn’t critical. Approval may be needed depending on your organization’s policies.

4.2 Implementation

1. Step 1: Configure the firewall to allow access to port 50070 only from trusted IP addresses or networks.
2. Step 2: If the web interface is not required, disable it in the Hadoop configuration file (hdfs-site.xml).

4.3 Config or Code Example

Before

# No specific configuration restricting access to port 50070 in hdfs-site.xml

After

<property>
  <name>hadoop.proxyuser.</name>
  <value>root,your_trusted_user</value>
</property>

4.4 Security Practices Relevant to This Vulnerability

Several security practices can help prevent this issue.

• Practice 1: Least privilege – restrict access to services and ports only to authorized users and systems.
• Practice 2: Network segmentation – isolate sensitive services like Hadoop NameNodes within a secure network segment.

4.5 Automation (Optional)

# Example Ansible task to configure firewall rules:
- name: Allow access to port 50070 from trusted network
  firewalld:
    port: 50070/tcp
    permanent: true
    state: enabled
    source: 192.168.1.0/24 # Replace with your trusted network

5. Verification / Validation

Confirm the fix by verifying that access to port 50070 is restricted as configured and that the web interface is no longer accessible from unauthorized networks.

• Post-fix check: Use netstat again to confirm port 50070 is listening, then attempt to connect from an untrusted host – it should be blocked.
• Re-test: Re-run the initial netstat command and verify that access is restricted as expected.
• Smoke test: Verify that authorized users can still access other Hadoop services (e.g., HDFS data nodes).
• Monitoring: Monitor firewall logs for any blocked attempts to connect to port 50070 from unauthorized sources.

netstat -tulnp | grep 50070

6. Preventive Measures and Monitoring

Update security baselines and implement checks in CI/CD pipelines to prevent similar misconfigurations.

• Baselines: Update your Hadoop security baseline to include a requirement for restricting access to the NameNode web interface.
• Pipelines: Add static analysis or configuration scanning tools to your CI/CD pipeline to detect open ports and insecure configurations.
• Asset and patch process: Implement a regular review cycle for Hadoop configurations to identify and address potential security vulnerabilities.

7. Risks, Side Effects, and Roll Back

Incorrect firewall configuration could block legitimate access to the NameNode web interface.

• Risk or side effect 1: Blocking authorized access – ensure that trusted IP addresses are correctly configured in the firewall rules.
• Risk or side effect 2: Service disruption – incorrect configuration changes may impact Hadoop cluster functionality.
• Roll back: Restore the original firewall configuration files if necessary.

8. References and Resources

• Vendor advisory or bulletin: http://www.nessus.org/u?090ac656