Methods and systems of improving security of a computing system having a network of embedded devices are disclosed. The method includes starting a timer of a predetermined length of time, obtaining an expected number of cyclic messages to be received within the predetermined length of time, incrementing a message counter each time a cyclic message is received within the predetermined length of time, incrementing a set counter in response to an actual number of cyclic messages received by the end of the predetermined length of time exceeding the expected number of cyclic messages to be received by a first threshold value, and detecting an intrusion in the system in response to the set counter exceeding a second threshold value by the end of the predetermined length of time.