Apache Spark Web UI Unauthorized Access Vulnerability
Description
Apache Spark is an open-source distributed computing framework that includes a Web UI for monitoring cluster operations, job execution, and system metrics.
By default, the Spark Web UI is not configured with authentication or access controls, making it accessible to anyone who can reach the network endpoint. This design assumes deployment in trusted, isolated environments where all clients are authorized. When exposed to untrusted networks or the public internet, the Web UI becomes accessible to unauthorized users who can view cluster information and potentially leverage this access for further exploitation.
Remediation
Restrict access to the Apache Spark Web UI using one or more of the following methods:
1. Network-level restrictions: Deploy Spark clusters behind firewalls or security groups that limit access to trusted IP ranges only. Ensure the Web UI ports (default 4040 for applications, 8080 for master, 8081 for workers) are not exposed to the public internet.
2. Enable authentication: Configure Spark's built-in authentication mechanism by setting the following properties in spark-defaults.conf:
spark.ui.filters=org.apache.spark.ui.SparkUIAuthenticationFilter spark.authenticate=true spark.authenticate.secret=<strong-secret-key>
3. Use a reverse proxy: Place the Web UI behind a reverse proxy (such as Apache HTTP Server or Nginx) with authentication enabled to control access.
4. Disable the Web UI: If monitoring through the Web UI is not required, disable it entirely by setting:
spark.ui.enabled=false
Verify that access controls are properly configured by attempting to access the Web UI from an unauthorized network location.