firmware update: http://swcdn.apple.com/content/downloads/15/22/031-87119/5a2wjh9sv5vsvkvdn2vx5s1oban3cpsuvw/FirmwareUpdate.pkg
full bundle update: http://swcdn.apple.com/content/downloads/15/22/031-87119/5a2wjh9sv5vsvkvdn2vx5s1oban3cpsuvw/FullBundleUpdate.pkg
embedded os firmware: http://swcdn.apple.com/content/downloads/15/22/031-87119/5a2wjh9sv5vsvkvdn2vx5s1oban3cpsuvw/EmbeddedOSFirmware.pkg