Embodiments are directed towards protecting against polymorphic cheat codes in a video game environment. A detour analyzer analyzes game code in client memory for possible hooks to parasite code. For each detected hook to parasite code, hook and/or parasite information is determined to generate a hook/parasite signatures, which are sent to a remote network device. Based on the hook/parasite signatures a weighted combination of scores are generated that is useable to determine a probability value that the parasite code is cheat code. If the determined probability value indicates cheat code, the user of the client device may be banned from future game play. Additionally, the hook/parasite signature information may be used to update the data store to detect polymorphic changes in the cheat code.