An install control module allows installation of a software application onto a computer in presence of malicious code that is attempting to prevent installation. A metamorphic installation program is generated randomly to be substantially unique using metamorphic stealthing techniques. The program can be installed and is executed on the computer. Identifying information in the metamorphic installation program is substantially disguised from the malicious code so the program is substantially unrecognizable. The software application is installed onto the computer, and the metamorphic program protects the installation to allow the software application to be installed without substantial interference from the malicious code. In another embodiment, installation occurs by booting a preinstall environment on the computer without running a primary operating system. The software application is installed offline without the primary operating system running and before malicious code present on the computer is executed.