1. A method comprising: selecting a set of printable characters as one or more test inputs for an unknown binary module having no known valid input; executing the unknown binary module with the set of printable characters as the one or more test inputs for the unknown binary module; determining, for each of the printable characters included in the set of printable characters, a number of instructions executed by the unknown binary module responsive to being executed with the set of printable characters; generating set data including the one or more printable characters associated with the number of instructions executed for each of the one or more printable characters; and analyzing the set data to identify one or more printable characters as one or more valid inputs for the unknown binary module based on a comparison of the number of instructions associated with the one or more printable characters and a threshold range.