A system and method for performing runtime de-obfuscation of obfuscated malicious software code in a virtual machine is described. According to one embodiment, the method involves enumerating a first physical page associated with a first virtual address space of a first piece of analyzed software code. Herein, the first virtual address space is a portion of a virtual address space associated with the virtual machine. Thereafter, the first physical page is set a non-writable permission. Hence, upon detection of a write to the first physical page by the first piece of analyzed software code, a determination can be made that the first piece of analyzed software code may be categorized as malicious software code.