Systems and methods of cyber hardening software by modifying one or more assembly source files. In some embodiments, the disclosed SME tool transparently and seamlessly integrates into the build process of the assembly source files being modified. For example, upon integration of the disclosed SME tool into the application's development environment, the modifications in the final executable are transparent to the developer and can support other cyber hardening techniques. The SME tool includes a preprocessing tool for identifying attributes (e.g., functions) associated with the assembly source file. The SME tool also includes a transformation tool for making modifications of the assembly source file. In some embodiments, the transformations correspond to applying one or more transformations to the attributes associated with the assembly source file.