The popular expert and Shodan creator John Matherly found over 650 terabytes of MongoDB data exposed on the Internet by vulnerable databases. Redis, CouchDB, Cassandra and Riak are equally impacted by these sorts of misconfigurations. The majority of vulnerable databases are hosted on cloud computing platforms run by Amazon.com, Alibaba Group and DigitalOcean.com. The data exposed in such databases was associated with 25 million user accounts from various apps and services, including 13 million users of the OS X optimization program MacKeeper.”]
Source: https://securityaffairs.co/wordpress/42897/hacking/mongodb-vulnerable-databases.html