The security afforded by Cassandra-level authentication and authorization only applies to clients connecting directly to your Cassandra cluster. Anyone who has physical access to the machines running Cassandra can access the data stored on disk; the same goes for anyone with SSH access to machines in the Cassandra cluster. Cassandra itself does not offer encryption for on-disk data, but DataStax Enterprise, a commercial distribution of Cassandra, does offer encryption of at-risk data. For more information, consult http://www.datastax.com/documentation/datastax_enterprise/4.5/datastax_enterprise/sec/secTDE.html.

Data security can also be compromised in transit; anyone who can intercept traffic between your application and your Cassandra cluster can potentially gain unauthorized access to your data. Cassandra offers client-to-node SSL encryption that protects your data...