This official guide published by Magento outlines a multifaceted approach to improve the security of your Magento installation. I was a co-contributor to the publication and also volunteered answering questions on both the Official Magento Community Forums and the Magento Stack Exchange site. Content from the forums posts that we created was used as the basis for this Magento Security Best Practices Guide.
Current Version: https://magento.com/security/best-practices/security-best-practices
Co-Contributors: