An illustrative method provides security of software resident on electronic gaming machines (EGMs) that permit wagering on games. A determination is made if all software files stored on a partition of a nonvolatile storage device resident in an EGM are authenticated image type files prior to any attempt to execute any of the software files. Further processing by the EGM of all of the software files is terminated upon the determination that one of the software files is not an authenticated image type file.