Security&privacy issues and challenges in NoSQL databases

Organizing the storing of information and data retrieval from databases is a crucial issue, which has become more critical with the spreading of cloud and Internet of Things (IoT) based applications. In fact, not only the network's traffic has increased, but also the amount of memory and the mechanisms needed to manage the so-called Big Data efficiently. Relational databases, based on SQL, are giving way to the NoSQL ones due to their efficiency in managing the heterogeneous information gathered from IoT environments. Such data can be stored, in a distributed manner, within the IoT network's devices or in the cloud. Hence, security and privacy concerns naturally emerge regarding access control, authentication, and authorization requirements. This paper analyses the current state of the art of security and privacy solutions tailored to NoSQL databases, particularly Redis, Cassandra, MongoDB, and Neo4j stores. The paper also aims to shed light on current challenges and future research directions in the field databases' security in the IoT scenario.