Apple has informed developers that, as of March 2012, any app submitted to the Mac App Store will have to include a sandbox. The move is an intriguing one from Apple, which has kept a low profile on security and typically handles Mac security on its own. Sandboxes in general are designed to prevent applications from taking actions that they shouldn t be allowed to take and stopping attackers from jumping from one compromised app to another. The iPhone has sandbox protection built into its iOS operating system.
Source: https://threatpost.com/apple-require-mac-apps-be-sandboxed-110311/75844/