Over the past two decades, malicious software, commonly known as malware, has become one of the largest threats to digital systems. File infectors, a class of malware, spread by injecting their malicious code into legitimate executables. Such infected files are routinely collected by cybersecurity vendors. The mixture of malicious and benign code in infected executables makes it challenging to detect and classify file infectors. This thesis presents a novel framework for the analysis of file infectors. Our framework takes a malware sample as input and examines the permanent modifications made to executables within a sandbox environment to determine if the given sample is a file infector.