Totally based on MySQL 5.6. It is a fork of some sort, old InnoDB release. The only link to MariaDB is with the MariaDB java Connector (there's a blog or two at blog.mariadb.org about this)

On Friday, 18 December 2015, Lukas Lehner <weblehner@gmail.com> wrote:
Hi

https://aws.amazon.com/rds/aurora/

Did Amazon write everything on their own?
Is it based on MySQL or MariaDB?

Lukas