1. Introduction
The Apache Hadoop YARN ResourceManager Unauthenticated RCE vulnerability allows a remote attacker to execute arbitrary code on affected systems. This is due to an unauthenticated API endpoint that permits system command execution. Successful exploitation could lead to complete compromise of the host and data loss. Systems running Apache Hadoop YARN Resource Manager are typically at risk, impacting confidentiality, integrity, and availability.
2. Technical Explanation
The vulnerability stems from a lack of authentication on the ResourceManager API, specifically allowing unauthenticated users to create and execute applications. An attacker can send a crafted HTTP request to this API endpoint to run commands with the privileges of the user executing the node process. This allows for remote code execution.
- Root cause: Missing authentication checks on the ResourceManager API endpoints, permitting arbitrary command execution.
- Exploit mechanism: An attacker sends a malicious HTTP request containing commands to be executed by the YARN ResourceManager. For example, sending a POST request with crafted parameters to create and execute an application that runs a shell command.
- Scope: Apache Hadoop versions are affected. Specific version ranges should be checked against vendor advisories.
3. Detection and Assessment
Confirming vulnerability requires checking API access control settings or identifying exposed endpoints. A thorough assessment involves attempting to exploit the endpoint with a test command.
- Quick checks: Check the ResourceManager web UI for authentication requirements on the API.
- Scanning: Nessus plugin ID 57624 can identify this vulnerability as an example.
- Logs and evidence: Examine ResourceManager logs for unauthenticated requests to the API endpoints. Look for suspicious activity or error messages related to unauthorized access.
# Example command placeholder:
# No specific command available without knowing the exact API endpoint URL. Check web UI.
4. Solution / Remediation Steps
The solution involves configuring ResourceManager API access control to require authentication for all requests. This prevents unauthenticated users from executing arbitrary commands.
4.1 Preparation
- Ensure you have access to modify the `yarn-site.xml` file. A roll back plan involves restoring the original configuration file and restarting the service.
- A change window may be required depending on your environment’s maintenance policies. Approval from system owners is recommended.
4.2 Implementation
- Step 1: Edit the `yarn-site.xml` configuration file.
- Step 2: Add or modify the `yarn.resourcemanager.api.authentication.enabled` property to `true`.
- Step 3: Configure appropriate authentication mechanisms (e.g., Kerberos, Simple Authentication).
- Step 4: Restart the YARN ResourceManager service for changes to take effect.
4.3 Config or Code Example
Before
<property>
<name>yarn.resourcemanager.api.authentication.enabled</name>
<value>false</value>
</property>After
<property>
<name>yarn.resourcemanager.api.authentication.enabled</name>
<value>true</value>
</property>4.4 Security Practices Relevant to This Vulnerability
Several security practices can help prevent this type of vulnerability. Least privilege reduces the impact if exploited, and input validation blocks unsafe data from reaching critical components.
- Practice 1: Implement least privilege principles for all services, limiting access rights to only what is necessary.
- Practice 2: Enforce strict input validation on all API endpoints to prevent the execution of malicious commands.
4.5 Automation (Optional)
# Example Ansible snippet:
# This is an example only - test thoroughly before use!
- name: Configure YARN ResourceManager API authentication
lineinfile:
path: /etc/hadoop/conf/yarn-site.xml
regexp: 'yarn.resourcemanager.api.authentication.enabled'
line: yarn.resourcemanager.api.authentication.enabled=true
notify: Restart YARN ResourceManager
5. Verification / Validation
Confirm the fix by verifying that API access now requires authentication and attempting to exploit the endpoint without valid credentials. A simple service smoke test should confirm core functionality remains operational.
- Post-fix check: Attempt to access the ResourceManager API without credentials. Expect a 401 Unauthorized error.
- Re-test: Re-run the earlier detection method (e.g., Nessus scan) and verify that the vulnerability is no longer reported.
- Monitoring: Monitor ResourceManager logs for failed authentication attempts or suspicious API activity.
# Post-fix command and expected output (example):
# curl -I http://your_yarn_rm_host:8088/ws/v1/timeline/metrics
# HTTP/1.1 401 Unauthorized
6. Preventive Measures and Monitoring
Update security baselines to include API authentication requirements. Implement checks in CI/CD pipelines to prevent unauthenticated endpoints from being deployed.
- Baselines: Update your Hadoop security baseline or policy to require API authentication as a standard control.
- Asset and patch process: Implement a regular patch review cycle for Hadoop components, ensuring timely application of security updates.
7. Risks, Side Effects, and Roll Back
Enabling API authentication may require changes to existing applications that access the ResourceManager API. A roll back involves reverting the configuration change and restarting the service.
- Risk or side effect 1: Existing applications may need to be updated with valid credentials to access the API.
- Risk or side effect 2: Incorrect authentication configuration could disrupt YARN functionality.
- Roll back: Step 1: Restore the original `yarn-site.xml` file. Step 2: Restart the YARN ResourceManager service.
8. References and Resources
- Vendor advisory or bulletin: http://www.nessus.org/u?57624ec9
- NVD or CVE entry: No specific CVE available in the provided context.
- Product or platform documentation relevant to the fix: https://hadoop.apache.org/docs/current/api_access_control.html