How to remediate – Apache Hadoop YARN ResourceManager Web Interface

1. Introduction

The Apache Hadoop YARN ResourceManager Web Interface was detected on a remote host. This interface allows monitoring and resource assignment for application execution within a distributed computing system. Its presence indicates a potential exposure point, as it could be accessed by unauthorized users if not properly secured. A successful attack could lead to information disclosure or denial of service.

2. Technical Explanation

The web interface is accessible over HTTP and provides an administrative console for the YARN ResourceManager. The primary risk stems from unauthenticated access, allowing attackers to view system resources and potentially disrupt operations. There is no known CVE associated with this specific detection, but it represents a configuration issue that requires attention. An attacker could use a browser or automated tools to enumerate running applications and resource usage.

• Root cause: The web interface is exposed without sufficient access controls.
• Exploit mechanism: An attacker connects to the YARN ResourceManager Web Interface via HTTP, potentially gaining insight into system resources and application details.
• Scope: Hadoop deployments using the YARN ResourceManager with an accessible web interface are affected.

3. Detection and Assessment

Confirming exposure involves checking for the running service and its accessibility. A thorough assessment includes reviewing network configurations and access logs.

• Quick checks: Use netstat -tulnp | grep 8088 to check if port 8088 (default YARN ResourceManager web interface port) is listening.
• Scanning: Nessus plugin ID 16479 can identify exposed Hadoop YARN Resource Manager Web UI. This is an example only.
• Logs and evidence: Review application logs for access attempts to the web interface, particularly from unexpected sources.

netstat -tulnp | grep 8088

4. Solution / Remediation Steps

The following steps limit access to the YARN ResourceManager Web Interface. These actions should be performed in a controlled environment.

4.1 Preparation

• Backups are not typically required for this change, but system snapshots are recommended. No services need to be stopped.
• Dependencies: Ensure firewall rules do not disrupt legitimate access. Roll back plan: Revert any changes made to the firewall configuration.
• Change window needs: A standard maintenance window is sufficient; approval from the infrastructure team may be required.

4.2 Implementation

1. Step 1: Configure the firewall to allow access only from trusted networks or hosts.
2. Step 2: If possible, disable the web interface if it’s not actively used for monitoring.

4.3 Config or Code Example

Before

# No firewall rules restricting access to port 8088

After

# Example using iptables:
iptables -A INPUT -p tcp --dport 8088 -s / -j ACCEPT
iptables -A INPUT -p tcp --dport 8088 -j DROP

4.4 Security Practices Relevant to This Vulnerability

Several security practices can help prevent this issue.

• Practice 1: Least privilege – restrict network access to only authorized users and systems.
• Practice 2: Network segmentation – isolate critical services like Hadoop YARN ResourceManager within a secure network zone.

4.5 Automation (Optional)

# Example Ansible playbook snippet:
- name: Allow access to YARN ResourceManager Web Interface from trusted network
  iptables:
    chain: INPUT
    protocol: tcp
    dport: 8088
    source: /
    jump: ACCEPT
- name: Drop all other traffic to YARN ResourceManager Web Interface
  iptables:
    chain: INPUT
    protocol: tcp
    dport: 8088
    jump: DROP

5. Verification / Validation

Confirm the fix by verifying firewall rules and checking accessibility from untrusted networks. A smoke test ensures core functionality remains operational.

• Post-fix check: Run netstat -tulnp | grep 8088 and verify that access is restricted to authorized sources.
• Re-test: Attempt to connect to the web interface from an untrusted network; connection should be refused.
• Smoke test: Verify that authorized users can still access the web interface for monitoring purposes.
• Monitoring: Monitor firewall logs for blocked connections to port 8088 from unexpected sources.

netstat -tulnp | grep 8088

6. Preventive Measures and Monitoring

Implement ongoing monitoring and security baselines to prevent recurrence.

• Baselines: Update a security baseline or policy to include restrictions on access to Hadoop YARN ResourceManager Web Interface.
• Pipelines: Integrate network configuration checks into CI/CD pipelines to ensure firewall rules are consistently applied.
• Asset and patch process: Review the configuration of all Hadoop components during regular asset reviews.

7. Risks, Side Effects, and Roll Back

Incorrect firewall configurations could disrupt legitimate access. A roll back plan should be in place.

• Roll back: Remove the added firewall rules using iptables -D INPUT ... (replace “…” with the appropriate rule details).

8. References and Resources

• Vendor advisory or bulletin: http://hadoop.apache.org/