Adobe Business Catalyst is a cloud based CMS solution for the development and implementation of business solutions on the web.
Unlike many other commonly used web development platforms such as WordPress or Joomla, BC was built with a single purpose in mind, to deliver web sites that embodied all the key aspects required of an online business presence within an easily managed and secure environment.
In simple terms, this is achieved by virtue of the fact that BC is NOT an open source system and the fact that developers can not upload to sites any executable code. The fact that ALL BC websites run froma common environment in the cloud also adds to the security layers with all servers hosted within Amazon data centres and fully managed by Adobe BC engineers.
Adobe Business Catalyst is PCI compliant
If you would like to read a more indepth explanation of the security measures in place please refer to the official Adobe Business Catalyst explanaton at http://docs.businesscatalyst.com/user-manual/e-Commerce/payment-gateways/security-and-pci-compliance-overview