How to remediate – Apache Hadoop HDFS DataNode Web Detection

1. Introduction

The Apache Hadoop HDFS DataNode Web Detection vulnerability refers to the presence of a web interface on nodes within a Hadoop Distributed File System (HDFS) cluster. This can allow unintended access to sensitive information and potentially enable unauthorized control over data storage. Systems affected are typically those running an Apache Hadoop HDFS cluster with exposed DataNodes. A successful exploit could lead to information disclosure, impacting confidentiality.

2. Technical Explanation

The vulnerability arises from the default configuration of DataNodes which includes a web interface for monitoring and management purposes. This interface is often accessible over HTTP without proper authentication or access controls. An attacker can discover this interface through network scanning and potentially gain access to cluster information, including storage details. There is no specific CVE associated with this detection; it represents a general misconfiguration risk. For example, an attacker could identify the DataNode’s web interface and enumerate available files on the HDFS system.

• Root cause: The default configuration exposes a web interface without sufficient security measures.
• Exploit mechanism: An attacker scans for open ports associated with the web interface (typically port 50070) and attempts to access it, potentially gaining unauthorized information or control.
• Scope: Apache Hadoop HDFS DataNodes are affected.

3. Detection and Assessment

To confirm whether a system is vulnerable, you can check for the presence of the web interface and verify its accessibility. A thorough method involves network scanning to identify open ports associated with the DataNode’s web service.

• Quick checks: Use netstat -tulnp or ss -tulnp to list listening ports and identify if port 50070 is in use by a Hadoop process.
• Scanning: Nessus plugin ID 90ac656 can detect the exposed DataNode web interface. This is an example only.
• Logs and evidence: Check system logs for any access attempts to port 50070 or related web service logs.

netstat -tulnp | grep 50070

4. Solution / Remediation Steps

To fix the issue, limit incoming traffic to the DataNode’s web interface port if it is not required for management purposes. Only apply these steps if you understand the impact on your Hadoop cluster functionality.

4.1 Preparation

• Services: No services need to be stopped, but consider the impact of firewall rules on management access.
• Roll back plan: Remove or disable the firewall rule if it causes issues with cluster operation.

4.2 Implementation

1. Step 1: Configure a firewall rule to restrict access to port 50070 to trusted networks only. For example, using iptables on Linux: iptables -A INPUT -p tcp --dport 50070 -s / -j ACCEPT; iptables -A INPUT -p tcp --dport 50070 -j DROP

4.3 Config or Code Example

Before

# No firewall rule in place, port 50070 is open to all networks

After

iptables -A INPUT -p tcp --dport 50070 -s 192.168.1.0/24 -j ACCEPT; iptables -A INPUT -p tcp --dport 50070 -j DROP

4.4 Security Practices Relevant to This Vulnerability

List only practices that directly address this vulnerability type. Use neutral wording and examples instead of fixed advice. For example: least privilege, input validation, safe defaults, secure headers, patch cadence. If a practice does not apply, do not include it.

• Practice 1: Network segmentation to limit access to sensitive services like DataNode web interfaces.
• Practice 2: Least privilege principles to restrict access only to authorized users and networks.

4.5 Automation (Optional)

# Example Ansible playbook snippet to configure firewall rules
- name: Block access to DataNode web interface
  firewalld:
    port: 50070/tcp
    permanent: true
    state: disabled
    zone: public

5. Verification / Validation

Confirm the fix by verifying that only trusted networks can access the DataNode’s web interface. Re-run the earlier detection method to ensure it no longer identifies an open interface.

• Post-fix check: Use netstat -tulnp or ss -tulnp and verify that port 50070 is only listening on trusted interfaces.
• Re-test: Run the Nessus scan again to confirm it no longer detects the exposed DataNode web interface.
• Smoke test: Verify that authorized users can still access other Hadoop services, such as HDFS file browsing or cluster monitoring tools.
• Monitoring: Monitor firewall logs for any unauthorized attempts to connect to port 50070.

netstat -tulnp | grep 50070

6. Preventive Measures and Monitoring

Suggest only measures that are relevant to the vulnerability type. Use “for example” to keep advice conditional, not prescriptive.

• Baselines: Update security baselines or policies to include restrictions on exposing unnecessary web interfaces.
• Asset and patch process: Regularly review Hadoop cluster configurations for potential security vulnerabilities.

7. Risks, Side Effects, and Roll Back

• Risk or side effect 1: Blocking legitimate access if the trusted network is incorrectly configured.
• Risk or side effect 2: Service disruption if firewall rules are too restrictive.
• Roll back: Remove the firewall rule using iptables -D INPUT -p tcp --dport 50070 -s / -j ACCEPT and restart the firewall service.

8. References and Resources

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