Elasticsearch is a search server based on Lucene. It provides a distributed, multitenant-capable full-text search engine with a RESTful web interface and schema-free JSON documents.
Your system has an ElasticSearch instance running (see www.elastic.co for more information) which is accessible on the internet. On its own, ElasticSearch does not support authentication or restrict access to the datastore, so it is possible that any entity that can access the ElasticSearch instance may have complete control.
This is especially problematic if this instance has dynamic scripting running. The scripting engine can be abused to launch a denial of service attack.
Either bind this service only to non-public facing connections or add a firewall to block the port ElasticSearch is running on.
Read the ElasticSearch documentation on how to properly secure your ElasticSearch instance.