Disclosed are various embodiments securing the execution of unauthorized applications on a computing device. A file system stored in a storage device includes files and file system data structures. The file system data structures have kernel space accessible portions. When a file is executed, a computing device can determine whether the file can be executed based on a file system data structure corresponding to the file based on the kernel space accessible portion. The operating system can determine whether to execute the file or take another action based on flags stored in the kernel space accessible portion.