CVE-2018-11770: Improper Authentication

Apache Spark standalone master exposes a REST API for job submission, in addition to the submission mechanism used by spark-submit. In standalone, the config property spark.authenticate.secret establishes a shared secret for authenticating requests to submit jobs via spark-submit. However, the REST API does not use this or any other authentication mechanism, and this is not adequately documented. In this case, a user would be able to run a driver program without authenticating, but not launch executors, using the REST API.